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XEphem Manual

1. SnDst SnLght Uranom Uran2k MIlISA Data Table percent of visible surface in sun light spherical angular separation between the Sun and given object calculated from the their geocentric ecliptic coordinates Note this is not just the difference in ecliptic longitude as is sometimes used The sign is positive for an evening object or negative for a morning object Thus this field is not generally useful in searching for eclipses because of the discontinuous sign change which occurs at conjunction For that use the individual Separations fields true heliocentric latitude in degrees For the Moon this is the geocentric latitude true heliocentric longitude in degrees Earth s is displayed on the Sun s line For the Moon this is the geocentric longitude galactic latitude in degrees galactic longitude in degrees ecliptic latitude in degrees ecliptic longitude in degrees true distance from Earth center to object center in AU except distance to the Moon is in miles or km depending on the Units preference time for light to travel from Earth to object Format is hh mm for all solar system objects except the Moon is in decimal seconds true distance from Sun center to object center in AU time for light to travel from Sun to object Format is hh mm Volume and Page number of object s location in the original Uranometria published by Willmann Bell Inc Volume and Page number of object s location in the new
2. if class is G or H the size field described next may include minor axis and position angle as subfields The remaining fields for Type f are as follows RA hours Declination degrees magnitude reference epoch optional assumed to be 2000 if absent size angular size arc seconds optional For elliptical objects such as galaxies this field may be divided into 3 subfields if desired the size of the major axis the size of the minor axis both in arc seconds and the position angle in degrees E of N These 3 subfields can also apply to double stars where the first subfield is the separation in arc seconds the second subfield is set to 0 and the third field is the position angle If the Type is e elliptical heliocentric eccentricity lt 1 the remaining fields are defined as follows i inclination degrees O longitude of ascending node degrees O argument of perihelion degrees a mean distance aka semi major axis AU n mean daily motion degrees per day computed from a 3 2 if omitted e eccentricity M mean anomaly i e degrees from perihelion E epoch date i e time of M D the equinox year i e time of i O o g k or H G two fields which define the magnitude model select which by preceding the first field with a g or an H 2 parameters If the Type is h hyperbolic heliocentric eccentricity gt 1 the remaining fields are defined as follows T epoch of perih
3. Moons are displayed only if they are geometrically visible Use the top view to see whether they are also in sun light Version 3 5 2 Page 9 1 Uranus View 9 1 Mouse functions The mouse may be used to identify any object in the Uranus view Position the cursor near the object of interest and select the right mouse button A popup menu will appear with the objects name current location and magnitude 9 2 Control menu Print This selection allows printing the current Jupiter view or saving it to a file Field Stars This selection activates the Field Star setup window For more information about this facility see the Help for the Field Star window itself 13 4 Telescope command This option causes the location of Uranus to be sent to a fifo The intent is for the fifo to be connected to a telescope control process This mechanism is the same as that provided by the Telescope facility within the Sky view Please refer to its help for more details in 10 6 Movie Demo This option will set up the Main window time step controls for a 15 minute step size and start a loop which dramatically displays the motions of the moons as they orbit Uranus This selection automatically disables the View gt Sky Background selection to insure reasonable speed Push the button again to stop the movie Close This removes the Uranus display and the additional information window if present from the screen 9 3 View menu To
4. designation Courtesy http ww aavso org GCVS stars Name and da Near last Sky View pick near last 204345 CV CYG y A GCVS name estos TSE 2040 44 NSV 13262 Sky View Tu CYG 2042 44A RR CYG cick Start ID or Daf gt idefault 20424 44B BZ CYG 2045445 V1661_CYG Start date End JD or Da latest 203046 TY CYG End date 7 WWW ARAVSO ORG UNEVALUATED DATA FOR TY CYG 2030 46 5 T T T T T T Observation Fainter than b 6f e E 74 Data from ajl AAVSO y EN gt Va een a 12 L 1 1 1 1 51100 51200 51300 51400 51500 51600 51700 51800 Julian Date 2 400 000 Get Curve Print Close Help This window provides easy access to the database of variable star light curves maintained by the American Association of Variable Star Observers AAVSO Many thanks to AAVSO for their support of XEphem First make sure your Internet connection is functioning The connection may be made directly or via a Proxy or SOCKS server These may be configured in the File gt Network setup window 2 1 1 To display a light curve 1 Enter the AAVSO Name or Designation in the fields in the upper left For example OMI CET for Mira If both are entered the Designation has priority 2 Entera range of dates for the data to be retrieved These may be given as a Julian Date or in the current Date format as set in the Main Preference menu The Starting date may also be given as default which is about 2 years of dat
5. 10 4 Images Menu oe ese cee 2 a2 ee eh a 10 18 10 4 1 Load and Save ccc cee eee n ne nen 10 18 10 4 2 Processing tools seer kortia eE REN eens 10 20 1043 WESSONWVE a a A ann 10 24 10 5 Locate menu at ee een 10 26 10 6 Telescope Menu 220 rennen nennen nennen nennen 10 26 10 6 1 Telescope configuration 0 0 0 ete 10 26 10 7 History menu ese eee os ee 2 sa m Di lea a 10 28 10 8 Iralls 22 oe a ee ee eel Gi Re 10 29 10 9 Scale controls in cece ia ce A ees ieee ale ek ee 10 29 11 Solar System VIEW cr aaa 11 1 11 1 Mouse controls un ee a een 11 1 11 2 Control Mmen 2 2 A a 11 2 113 View Menu eier ia 11 3 11 4 Objects menu 2 2 ee re ae 11 3 11 5 Scales Sas oie ee ee ale ti ge Ga ae eee a ee 11 4 12 TOD A eee ia oh ee wee eee bade we 12 1 12 1 Plot valueS 2 2222 A aera See ae cares 12 1 Taa LISt Values in as o ds ae debaters Matas Mek arctan tals 12 3 12 3 Solve equation 2 2 2 icy Sie ee a ee din eee ee eee Pe tee 12 4 12 4 FING ClOSC Pals nese eek ieee ieee eee ahd ne 12 7 124A Control Menu eves air ss a RE FRE Ra a eh 12 7 12 4 2 Options MENU uses tee sel ee pe dee a Daren eh 12 8 12 5 Night at Glance ici iii a ich 12 9 12 6 AAVSO light CUrVeS o oooccccoco annnars 12 10 12 7 SETI home 4 a a ana ea an 12 11 12 8 Coordinate Converter ooococoocco eens 12 12 13 Datla cick cea cir be a ie been we a 13
6. 8 1 01 2001 7 01 2001 1 01 2002 2 7 6 Ring crossing This example will demonstrate the programmable equation solving feature by Page 2 22 Version 3 5 2 Main Window solving for the time when the Earth crosses the ring plane of Saturn Generally when using the solving feature of XEphem a plot of the function should be made first to investigate the general behavior of the function over time and to form an initial estimate of the solution Hence our first step is to make a plot of ring plane angle throughout 1995 Use UTC for all time displays Main gt Preferences gt Time zone gt UTC Set the date to Jan 1 1995 Main gt Local Date gt 1 1 1995 You might have to enter this differently depending on your current Date Formats preference You could also set the date by using the interactive calendar at the right select the current month slide and release over January then push the 1 date on the calendar Do the same sort of thing to set the year Set the time to UTC midnight Main gt UTC Time gt 00 00 00 Bring up the Saturn diagram and supporting information views Main gt View gt Saturn Saturn gt View gt More info Bring up the plot control window Main gt Tools gt Plot Select one function to plot UTC Date vs Earth ring tilt Plot gt Select fields turn on Main gt UTC Date Saturn info gt From Earth Plot gt Select fields turn off Specify plot file name and gi
7. Details o 19 Minor resources have been modified since last Save Gr vate vase Sear UIT E Earth XEphem Earth cylindrical set False P XEphem Earth grid set True Click On to XEphem Earth livedrag set True force Save XEphem Earth sites set True XEphem Earth spherical set True XEphem Earth sunlight set True XEphem Earth wxmap set False The following Minor Resources are never automaticaly selecte XEphem Earth height 404 Contains at least one xEphem Earth width 371 Major resource different ee z from value last saved HEnhemekarthoh3e k 55 XEphem EarthObjs y 328 Help Jupiter Main Basics Main Preferences Main Preferences Colors Contains no Major but at least one Minor resource different from Haine Wes ln value last saved o Main Preferences Save Mars Features Mars View and Info o Network o Night at a Glance Saturn o Sky View FRAPS Sky View Filter Save Refresh Close Help This window displays all of the options settings and controls throughout XEphem which may be saved and reinstated next time the program is started These are collectively referred to as Resources and in fact are saved using the standard X Windows resource database mechanism XEphem uses many resources so they are separated into categories in this window for easier management Each category may be expanded or collapsed using the and control toggles to show each individual resource if desired Resources have
8. Each data item occupies one column in the table and each object occupies one row The Control pulldown menu contains the following options Setup This button brings up a configure window to specify the table rows and columns as desired List This button allows the current data table to be saved in a text file When any columns related to rising or setting are active a box at the bottom will indicate whether the times refer to the center or the upper limb of the object Similarly when either the RA or Dec columns are active or any of the separation columns are active a box will be present to indicate whether the separation is from a geocentric or topocentric point of view The box will also indicate the precession epoch See the help for the Setup window for more information about these modes Any of the information in this table may be plotted 12 1 listed 12 2 or used in a solver algorithm 12 3 See the help for these control functions for more details See the help for the Setup window for a description of each column 3 1 Setup window Rows Columns Objects Miscellaneous Rise Set Separations Toggle Toggle Toggle Toggle All All All All Reset Reset Reset Reset Sun Cns I Helat 9 Sun Moon RA HeLong Limb 3 Moon Mercury HA GLat Center Mercury venus Dec GLong RisTm Venus F Mars Az EcLat Ris z Mars Jupiter Alt EcLong M TrnTm Jupiter F Saturn M Zenith H EaDst Trnalt Saturn Uranus Air Ealght m SetTm
9. Midnight Time stepping Main Window This describes the features of the Main XEphem window Across the top is a menu bar to allow selecting the principle functions of XEphem Each window opened from the menu bar has its own Help Only a few specific entries will be mentioned here Help gt on Context turns the cursor into a Question Mark Roaming the cursor over any control in XEphem will show its bubble help tip Press the left mouse button to end this behavior and resume normal operation Help gt Search allows you to search the entire Help database for keywords Each matching entry will be displayed highlighted in context and the search may be easily repeated to look for additional occurrences Go Below the main menu bar is the XEphem logo image Beneath that is a status line that contains a short description of what XEphem is doing at the moment with regards to its looping behavior see Help gt on Operation Below the status line is room for the NEW CIRCUMSTANCES message When you change any field on the Main window that could invalidate any of the other fields or views throughout XEphem this message flashes until at least one screen Update occurs to get everything up to date again See Help gt on Operation 81 5 for more information on changing the fields in the Main window and controlling XEphem s run time behavior See the Help gt on Triad formats 81 6 for more information on date time and
10. Note that larger separations result in larger lists and hence longer sorting times Also set other options via the Options menu Separations will be topocentric or geocentric depending on the Equatorial preference in the Main menubar Then start the scan via the Update button in the Control menu When the scan completes all pairs meeting the criteria will appear in the scrolled list The columns in the list are as follows Magnitude_1 Name_1 Magnitude_2 Name_2 Separation The entries are sorted in increasing order of separation The total number of pairs and current conditions are reported above the list and the time when the scan was performed is indicated in the time stamp label below the list The scan does not include field stars 12 4 1 Control menu Update This performs one scan The XEphem cursor will change to the Watch shape until the scan is complete The results are listed in the scrolled list when complete Sky Point This will place a cross hair over the first object of the selected pair on the Sky View re aiming if it is currently not in the field Either select the pair in the list then press this button or double click on the pair in the list These commands do nothing if the Sky View is not currently up List to file Version 3 5 2 Page 12 7 Tools This selection allows writing the current collection of close objects to a file A window is presented which allows you to enter a file name If the file does not e
11. Psi_2 exp 1 87 psi_t m H 5 0 log10 rp rho 2 5 log10 1 G Psi_1 G Psi_2 where m resulting visual magnitude rp distance from sun to object Version 3 5 2 Page 13 9 Data rho distance from earth to object rsn distance from sun to earth Note that this model does not take into account the phase angle of sunlight The H G model is the default magnitude model for elliptical objects but it can also be explicitly indicated when the first of the two magnitude fields is preceded by a letter H This works in both the edb database file and the corresponding menu elliptical object definition prompt 13 3 3 Hyperbolic objects Hyperbolic objects are characterized by 10 parameters the parameters that define a heliocentric hyperbolic orbit and the magnitude model coefficients These orbital parameters are in order T epoch of perihelion i inclination degrees O longitude of ascending node degrees o argument of perihelion degrees e eccentricity q perihelion distance AU D the equinox year i e time of i O o g k two fields for the magnitude model s angular size at 1 AU arc seconds optional As with elliptical elements other parameters might be available The relationships are generally the same except for q a e 1 The g k magnitude model requires two parameters to be specified One the absolute magnitude g is the visual magnitude of the object if it were one AU from both
12. and are adjusted automatically as the solution proceeds Note that by setting N Steps to 1 and repeatedly selecting Update you can effectively single step the process Solving will automatically turn off when convergence is detected the function is edited or you may turn it off manually at any time by toggling the button labeled Solving is Active back off Additional notes on using the equation solver When selecting fields for plotting or listing a button appears labeled Use for plotting You may select this button to use the evaluated function as an item in the plot or listing feature Note that the function may be used in plotting and listing whether or not actually solving is enabled The windows which contain the fields used in the function being solved need not be visible while solving is in progress The Close button removes the Solving window from the screen it does not effect actual solver operation in any way A successfully compiled function is evaluated each time XEphem updates Whenever the function is compiled it is also evaluated using freshly updated values In this way the Solve window can actually be used as an arbitrary astronomical calculator at any time whether or not solving is actually active Hint Solving periodic functions can lead to solutions far from the intended range You will get best results if you can start the search near the expected answer and with a small step Version 3 5 2 Page 12 5
13. gt View gt Cylindrical Page 2 26 Version 3 5 2 Main Window Set your location click on the button below Location in the Main window scroll through the list and click on a city near you click Set click Close in Main click Update at the bottom To get a quick idea of all times when IIS is visible at your location click on Main gt Tools gt Night at a glance the dotted light near the bottom shows all times when IIS is visible between noon today and noon tomorrow To see the next time ISS will rise in your location click Main gt View gt Data table The next rise time is in the RisTm column If this column is not visible bring up Control gt Setup toggle Rise Set gt RisTm so it is On click Apply The highest it will get on this pass is in the TrnAlt column If this column is not visible bring up Control gt Setup toggle Rise Set gt TrnAlt so it is On click Apply Note the RisTm from above and set the the Date and Time in the Main window to about 30 seconds or so later Be sure to use UTC or Local depending on Main gt Preferences gt Time zone Show the path overhead in the Sky View check that Main gt Preferences gt Equatorial is set to Topocentric click Main gt View gt Sky View check that Sky View gt Control gt Options gt Orientation set to Alt Az slide the FOV to a full 180 degrees click Sky View gt Locate gt ISS to mark the ISS on the sky map move the mo
14. 2 5 Preferences MenU 220 c cece eee nennen nennen nenn nenne 2 7 2D NS AVE iad nuts a a er Meters MD EE en he REN Re 2 9 2 5 2 Save FOS us a ae ann reinen 2 11 203 Save COMOMS en na en ee are tea ee ehe Doma Pie aa A A 2 12 2 0 Sites dialog en Feet taf 2 0 2 en a ai 2 13 2 7 SEXGMPlOS esi tec OS O 2 14 27 1 SKY OO feck Be es ee bt ete nen ot ees 2 14 2 7 2 Solar eclipse path ersa kaain ma a ia teens 2 16 LAS SKY A re ee en tt e i 2 17 2 14 Displaying Images 2 sehe tn terre Den tet Sehe bler seme 2 19 2 1 9 SUNIISEIPIOR 2 20 ea nn degen Lee wenn Se eee ae 2 20 2 16 RING COS SIM aia a tia Bier ead ek BED Siem ears 2 22 2 7 7 Lunar occultation 1 0 0 00 eee 2 25 2 7 8 International Space Station 0 00 eee 2 26 3 Data Fable EA AAA rer 3 1 3 1 Setup WINDOW 2 22 eg een eee ee 3 1 4 MOON VIEW sa He 4 1 4 1 Mouse functions 0 ii Ba ar nee ees 4 1 Version 3 5 2 Page i i 4 2 Control MON sii ca Ra Shan ead 4 2 4 3 VIEWS MENU u su a A I Gee NE 4 3 4 3 1 More info dialog 0 ce eee 4 4 4 4 Scale Menus 2 22 Se hk A A ale 4 5 ESTIMA kis 5 1 5 1 Mouse functions 4 a a ei a a 5 2 5 2 Control Menu un A la ann Ae dala ee wee 5 2 52 1 Objects dial rs a SER Inn i aes Bin I 5 3 5 3 VIEW men ierit Hr Hi a 5 5 Mars VIW au aa naar 6 1 6 1 Mouse functions risie ee A ee na 6 1 6 2 Control men iii ee a eet a 6 2 6 3 VIEW MENU 26 224 202 Posie A ee een eed
15. 6 2 6 3 1 More mo dialog 1 2 otero nea nee 6 3 6 3 2 Moon info dialog e e ara es t eg iae a A eee 6 3 J piter VIEW ana ee RN Ec 7 1 Tal Mouse functions 2 bis ee Re ee 7 2 TZ CONTO men cs sec oo U Dar 7 2 1 3 NIEW MENU see aaa a nn ni Ne ae en 7 2 7 3 1 More into GlalOG iis zur poke Hess sks pie Pe eee Desk 7 3 Saturn VIC Wee ee elon tn Owe nana erase ae Mace none 8 1 8 1 Mouse functions eesi t naa un a 8 2 8 2 Control MENU cocida Her ale 8 2 8 3 VIEW MENU ri ae el a ee dida 8 3 8 3 1 More info dialog 2 2 eee 8 3 Uranus VIEW co en Ek eee A Boas 9 1 9 1 Mouse functions crte cassia dead ee tee a ee 9 2 9 2 CONTO Menu wi sock eee eines one etek 9 2 9 3 View men Ya ni 9 2 9 3 1 More info dialog p En sonne nennen nennen 9 3 10 SKY views ee aa a ou 10 1 10 1 Toolbars 25H ae a I DIR ie 10 2 10 2 Mouse functions 0 000 aaa ua 10 3 10 3 6ontr l Menu nov cot ea ae en eae eee le 10 6 10 31 OPIO rear Ved ita a lial eae Seon neon an sa hae dd 10 8 10 32 Eller a debian ae vs alien 10 12 VOS PAM a DA Be ee ee 10 12 TONSA MES ties cca cies oe telco Ans ee a era de Ae eve at ie 10 13 1023 5 Horizon un rn Aa Heist en toe Agrees BAG rein 10 14 10 30 Held Stars 222 sige a te er ee ee Peeps AI 10 15 10 3 2 Eypio Sa ass a AGA a RA Gd edi 10 16 Page i ii Version 3 5 2 10 38 Coordinate Shu gee id Gat eed ee ai ee 10 17 10 39 LACKING 30 Hr see ee A nal 10 17 TORTOSA a a jaa 10 17
16. A Canzian B Harris H Reid N Rhodes A Sell S Ables H Dahn C Guetter H Henden A Leggett S Levison H Luginbuhl C Martini J Monet A Pier J Riepe B Stone R Vrba F Walker R 1996 USNO SA1 0 U S Naval Observatory Washington DC This catalog has been included with permission of USNO as long as we mention the follow stipulations It may not be the latest version check with http ad usno navy mil If you paid for XEphem you paid for the software not this catalog The catalog is available free from the USNO Inclusion of the SA2 0 catalog does not imply an endorsement of XEphem by USNO nor did have privileged access to the catalog nor does the US Government affirm or guarantee that XEphem works properly in any way Proper Motion catalogs Version 3 5 2 Page 13 13 Data These catalogs include information regarding proper motion The position of the star is moved to its location according to the current XEphem time when the stars are loaded In order to see a movement change the time and watch carefully Two such catalogs are currently available ready for XEphem You may only use one at a time by choosing the corresponding toggle PPM catalog This is the Positions and Proper Motion catalog of S Roeser and U Bastian Astronomisches Rechen Institut Heidelberg published in 1990 The PPM includes 468 586 stars rather evenly distributed throughout both hemispheres This a
17. Equinox is set to EOD this is the apparent place otherwise it is the astrometric mean place If Main Preference Equatorial is Topocentric it is further corrected for parallax HA geocentric or topocentric hour angle of object computed as LST RA precessed to EOD Positive angles are west of the meridian GHA Greenwish Hour Angle hour angle of object when at 0 longitude Dec Declination if Main Equinox is set to EOD this is the apparent place otherwise it is the astrometric mean place If Main Preference Equatorial is Topocentric it is further corrected for parallax Az topocentric degrees eastward of true north for object Alt topocentric degrees up from a horizontal plane that is Elevation feet above sea level Corrected for refraction Zenith topocentric Zenith distance degrees corrected for refraction Air Number of relative air masses through which light from the object passes to the topocentric observer Computed by the method of Hardie clamped to a max at 3 degrees altitude Spect Basic spectral classification if appropriate Size angular size of object in arc seconds If not otherwise given estimated for objects in heliocentric orbits from the absolute magnitude parameter H and by assuming an albedo of 0 10 for which H is 18 for an object of 1 06 km diameter at 1 0 AU VMag visual magnitude of object Page 3 2 Version 3 5 2 Phase Elong HeLat HeLong GLat GLong EcLat EcLong EaDst Ealght
18. N 73 59 39 W 16 8 EST5EDT Sydney Australia 33 52 0S 15112 OE 7 6 EST 10EST M10 5 0 M3 5 0 Lines in the file which do not conform to this structure are ignored 2 7 Examples Follows are some example goals and worked solutions to practice using some of the XEphem features 2 7 1 Sky tonight This example will take us through a session which explores the sky tonight at midnight Of course you can do this for any night by setting the desired date first on the Main window Set time to midnight tonight Main gt Local Time gt Midnight Tonight Page 2 14 Version 3 5 2 Main Window Main gt Update Display the available database files Main gt Data gt Load and Delete Load up several database files as desired by double clicking in the list at at the bottom Data Base gt YBS edb Yale Bright Star catalog Data Base gt Messier edb Messier catalog Data Base gt NGC edb RNGC objects all but Messier Data Base gt SAC edb even more deep sky objects Data Base gt asteroids edb many asteroids Bring up the sky view Main gt View gt Sky View Explore around using mouse pointing and or by sliding field of view and pointing controls as desired Save the objects in the Sky View in a file Sky View gt Control gt List Make a printed copy Sky View gt Control gt Print Now let s focus in on some close encounters Let s switch to RA and Dec coordinates tighten up the field and increas
19. Uranometria 2000 edition Volume and Page number of object s location in the Millenium Star Atlas published by Sky Publishing Corp Column three controls information related to rising transitting and setting These are computed based on a refraction model that uses the actual atmospheric and topocentric circumstances displayed on the Main window A text entry field is available in which you may specify a number of decimal degrees the local horizon is above horizontal to account for local effects The Limb option means that the rise and set circumstances are based on the location of the upper limb of the object Center means that the circumstances are based on the location of the center of the object Follows is a description of the Data Table columns controlled by the third Data Selection column Version 3 5 2 Page 3 3 Data Table RisTm RisAz The local or UTC time and azimuth when the upper limb or center of the object rises TODAY See note below for Earth satellites TrnTm TrnAlt For all but Earth satellites this is the local or UTC time and altitude when the object crosses the meridian TODAY i e when its azimuth is true south or if no precession when the local sidereal time equals the object s right ascension If the object is an Earth satellite this is the time and highest altitude the satellite ever reaches above the local horizon at whatever azimuth SetTm SetAz The local or UTC time and azimuth when the u
20. altitude The effect is remarkably significant For example it is more than two arc minutes at a height of 5 feet 2 Libastro is based on VSOP87 For Mercury Venus and Mars the accuracy of this model rises to 1 at the ends of the year range 2000 4000 For Jupiter and Saturn the 1 range is 2000 2000 For Uranus and Neptune it is 2000 6000 For the Moon 1 accuracy is for the range 1369 to 2950 Other heliocentric objects are well within one arc minute at the time of the epoch of their elements this steadily worsens with time since XEphem does not apply perturbations Using a GPS position locator and transit have independently verified Sun and Moon limb rise and set times are accurate to within one minute and azimuths are with about 0 1 degree 3 The Sun Moon distance is the solution for the third side of a planar triangle whose two other sides are the Earth Moon distance and Earth Sun distance separated by the angle of elongation 4 The visual magnitudes for the planets take into account the phase of the illumination the magnitudes for other solar system objects do not 5 The following is the current TODO list of ideas for XEphem Thanks to all who have made suggestions Please let me know your priorities or suggest more write a tool to find g k from a set of predicted magnitudes add undo for plot and listing selections display occultation path between any two objects in the Earth view show correc
21. are also available via the tool bars across the top and down the side of the Sky View The top tool bar offers shortcuts to What is being displayed such as grid overlay annotation galaxies the one down the left controls How it is displayed such as brightness display mode flipping To learn what each icon in the tool bars does use Help gt Context from the Main window and move the cursor over each icon to cause it to display its help tip bubble Display mode Alt Az Sphere R Dec Cylinder Grid Control Grid Auto Dec 0 01 00 RA 0 00 05 Alt Az Labels RA Dec View Options Just dots Flip Left Right Flip Top Bottom Equatorial plane Ecliptic plane Galactic plane Eyepieces Magnitude key Auto magnitude ield stars Live dragging Horizon map Constellation Boundaries Figures Full names Abbreviations Labeling Stars Sol Sys N MDeep Sky Help Close Page 10 8 Version 3 5 2 Sky View Display mode Alt Az RA Dec This radio box selects whether the display coordinate system is Altitude Azimuth or Right Ascension Declination NOTE While in Alt Az mode the display is always topocentric while in RA Dec mode the display coordinate system depends on the Equatorial preference and Equinox settings in the Main window Sphere Cylinder This radio box selects whether the display is projected onto a sphere on a cylinder The advantage of the sphere is that it mimics the real sky The advanta
22. be displayed for Stars Solar system and Deep sky objects Note that trails and persistent labels are not subject to the faint magnitude limits The fourth scale in the lower left selects the number of magnitudes binned in each dot size Several push buttons appear across the bottom of the Filter window which have the obvious effects Selecting Apply updates the sky display according to the desired selection Selecting Ok does the same thing but also closes the Filter window All turns on all types Toggle toggles each filter type 10 3 3 Print This selection allows printing the current Sky view or saving it to a file If an image is currently being displayed it will also be part of the print image It has its own Help 14 Page 10 12 Version 3 5 2 Sky View 10 3 4 List List Sort and Save current Sky View objects Choose format and set file name for Save edb home ecdowney xephem skyl ist edb Text home ecdowney xephem skylist txt Pick sort keys in desired order Name Size Elongation Venus Sep Type Magnitude Rise time Mars Sep Constellation Helio lat Rise azimuth Jupiter Sep Right Asc Helio long Transit time Saturn Sep Hour angle Galactic lat Transit alt Uranus Sep Declination Galactic long Set time Neptune Sep Azimuth Ecliptic lat Set azimuth Pluto Sep Altitude Ecliptic long Sun Sep Obj X Sep Zenith Earth dist Moon Sep Obj Sep Air mass Sun dist Mercury Sep Obj Z Sep List 90 objects Choose colum
23. black and white to the mean 1 3 Std Dev Wide assigns black to mean 1 StdDev and white to mean 2 StdDev Full assigns black to the smallest pixel and white to the largest pixel in the entire image Sharper and Duller change contrast by changing the slope of the pixel to brightness map to be steeper or flatter Brighter and Darker change the brightness by shifting the center of the pixel to brightness map to higher or lower pixel values Nominal ignores the statistical distribution of pixel values and sets the map entirely on the basis of the minimum and maximum pixel Below the buttons are text fields in which one may type or paste the exact pixel value to be assigned to black and white They always show the current settings A new value takes effect when Enter is pressed Below that is a scale to adjust Gamma The mapping from pixels to display colors is a power function similar to the Gamma factor for CRT compensation Values of gamma less than 1 emphasize dark pixels gamma values greater than 1 emphasize bright pixels The graph contains two overlaid plots The horizontal axis for each plot is the same the full range of pixel values within the image with lowest on the left The orange line is a histogram of the number of pixels with each value The yellow line indicates the brightness at which each pixel value will be displayed on the screen You may control the black and white limits of the mapping function from the graph b
24. circles at the edges of the umbra and penumbra during a Lunar eclipse Version 3 5 2 Page 4 3 Moon View Flip T B This sets whether the image is flipped top to bottom Flip L R This sets whether the image is flipped left to right Grid This sets whether a coordinate grid is drawn over the image Each line is spaced at an interval of 15 degrees Also the current subearth location is marked with an X the subsolar point is marked with a small open circle and the anti subsolar point is marked with a small filled circle 4 3 1 More info dialog This brings up a separate window with additional information Under Cursor Latitude N 33 47 Longitude E 325 12 Sun altitude 15527 Next Sunrise 13 29 12 06 2000 Next Sunset 19 07 11 21 2000 Sunrise Long 163 04 Subsolar Lat 1 10 Libr in Lat 5 56 Libr in Long 4 41 Limb angle 218 17 TALE Heda 11 20 2000 7 56 07 UTC Close The top portion of the window reports the location of the cursor as it is moved over the image if the left button is pressed It also shows the altitude of the Sun and the times when the Sun will next rise and set at that location The times are in accord with the Time zone Preference in the Main window The lower portion of the window shows the lunar longitude of sunrise the lunar latitude of the subsolar point and libration information The longitude of the subsolar point is at 90 from the sunrise longitude and the longitude of the an
25. coordinate formats Follows is a description of each of the display fields in the Main window Local Site name Latitude Version 3 5 2 See below Local geocentric latitude positive degrees north of equator Changing this will disable automatic computation of Daylight Savings Time Page 2 1 Main Window Longitude Elevation Temperature Atm Pressure Equinox Time UTC Date UTC Time Julian Sidereal TZ Name TZ Offset Local Date Local Time Delta T Page 2 2 Local longitude positive degrees west of Greenwich meridian Changing this will disable automatic computation of Daylight Savings Time A sensible Timezone is created based on one hour for each 15 degrees from 0 Local elevation of the ground above sea level in feet or meters see implementation notes Used in topocentric parallax correction Local surface air temperature in degrees F Used in refraction correction Local surface air pressure in inches of mercury Used in refraction correction When set to a year this is the desired epoch to which the RA Dec fields are precessed referred to as the astrometric place When this is set to EOD all RA Dec values are precessed to the current XEphem time and corrected for nutation aberration and deflection referred to as the apparent place The UTC date UTC is Coordinated Universal Time the basis after adjusting for time zones for the official civil time people set their cloc
26. for more information 13 3 Set Object ISS ZARYA Moon Moon Display Label Trail Center Popup Obj SubLat 10 05 34 16 57 26 16 57 26 SubLong 60 06 19 106 13 15 106 13 15 AltCkm 380 Range km 11484 Range m s 1604 Sun lit 0 Ageldays 31 28 11 25 2000 18 46 11 UTC Close Help Several controls and information values are available for each object as follows Display This controls whether the selected object is shown at all If it is visible the object is drawn with a bulls eye pattern Each circle of the bulls eye indicates the locus of points where the object appears in the sky 0 30 60 and 90 degrees from the zenith Label This controls whether the name of the object is drawn above it current location Version 3 5 2 Page 5 3 Earth View Trail This control will bring up a window to define a ground track of the given object as it travels along its orbit Each trail time is drawn connected with a solid line with each point indicated with a small mark The time stamps shown with the trail if any are always in UTC Once a trail is defined this toggle just turns the trail On or Off on the display It will not bring up the Trail window again unless the trail gets deleted The trail will be deleted if the object is changed or an Update occurs from the Main window while this toggle is Off Creating a new trail will also delete the old one See the Help from the trail setup window itself for mor
27. have been specified and the listing file named and titled if desired select the Create list file toggle button Now each time XEphem goes through one iteration the values you have selected will be written to the file Note that when listing is activated XEphem does not update the screen until the N Steps count goes to 1 This greatly speeds the creation of listing files by avoiding screen updates If you wish to watch each iteration set N Steps to 1 and select the Update button manually for each iteration Once all the desired data have been entered into the listing file toggle the list button back off to flush all data and close the file Menus that contain each of the fields used in the listing need not be visible for the fields to be listable 12 3 Solve equation This window controls the automatic equation solving facility You define an arithmetic or boolean function using most of the fields XEphem displays then XEphem will automatically evaluate the function and adjust the time on each iteration to solve for the goal To set up a function to solve follow these steps Enter a function Compile it Select a goal Set the desired accuracy Enable solving Start the solving process Each of these steps is described below Entering the function The function may be any arithmetic expression in C language syntax All of C s comparison logical and arithmetic operators are supported as well as several common ari
28. in um mm in D M S W gt 50mm 351m 40 03 20 0 Apparent field Apparent Eyepiece Mirror FL through eyepiece n FOV FL mm Cmm min H W i rE f 3 0 16 12 0 H Real field of view Eyepiece focal K5 pi 2mm 2000m 16 12 0_ H length onsky i i Sav orite Eyepieces Add mirror z Gaan A Del Use My eyepiece 1 gt o Save current definition Del Use My eyepiece 2 1 04 2 25 RS I in favorites list Delete this definition L Del Use My eyepiece 3 2 25 4 02 E 0 i from favorites list SE Width height h nd styl Delete all Sky View eyepieces shape and style Use this codes definition Gloss Help next 2 Name for this Delete only if at least definition This window allows you to specify the shape size and style of the next eyepiece marker to be placed in the Sky View These markers are useful to show the view through your eyepiece simulate the view of a CCD camera or as simple annotation markers for any desired purpose Symbology on the map will show through the eyepieces even when they are specified as solid Note that this window controls the style of the next eyepiece to be created To actually create an eyepiece place the mouse over the Sky view where you want the center to be located and press the right button A popup menu will appear Slide down the menu and release over Place eyepiece See below for how to delete eyepieces Across the top are two sliders which set the width and height of t
29. is available in the Data Table window see its Help for more information If a trailed object is selected the data will be as it was at the time for that position If the cursor was not near an object basic information based on the location of the cursor itself is shown The popup also offers several control operations as follows At any one time only the ones relevent to the current situation and toolbar choices will appear Center This will change the Sky View pointing direction to place the given object or location at the center of the field of view Center Zoom gt This will change the display orientation to place the given object or location at the center of the field of view and at the same time zoom in or out the amount selected in the pullright cascade menu Place eyepiece This will cause an eyepiece symbol to be drawn centered under the mouse location The eyepiece shape and size is defined in the Eyepiece Setup window available via Control gt Eyepieces 10 3 7 Delete eyepiece This will delete the closest eyepiece covering this mouse location if any The search algorithm uses the smaller of the two dimensions of the eyepiece so it may be necessary to get close to the center depending on the shape New Photom ref This only appears if an image is being displayed the 2D Gaussian image analysis tool is up and the cursor was clicked near a database object If all this is so then said object is used
30. is commanded to a target by positioning the cursor at the desired location in the Sky View press and holding the right mouse button and sliding down and releasing on Telescope GoTo Each time this action is performed the target name or RA Dec coordinates if sent to an empty sky location is added to this Telescpoe menu To command the telescope to the same target again just slide down and release on its entry The list will grow until erased using the Erase history button 10 6 1 Telescope configuration This window is for configuring an LX200 connected to a serial port of the computer running XEphem There are casks pein UDSSR just a few fields to be filled out e AEEYSU Show Sky View marker Enable Telescope GoTo Use no hardware test mode when next restarted Page 10 26 Version 3 5 2 Running Close Help Sky View Control process This field names the driver program that does the real work The name Ix200xed is the one for the LX200 command set This should not be changed unless a new driver has been supplied Serial device This is the name by which your operating system designates the RS232 serial port connected to the telescope The default will be close for a typical installation See the chapter in the manual for more information about specific operating systems Show Sky View marker Once the telescope is working under XEphem s control a circle X marker will be drawn on the Sky View to indicate its current pos
31. location of the work unit to user definable object Obj Z 813 3 doing so will add it to the Locate pulldown menu of the Sky View and add it to the View gt Data table for easy reference 3 Auto refresh When this toggle is active a Refresh is performed automatically every 10 seconds This toggle is turned off when the window is closed The large text box contains some report details Most entries are taken directly from the setiathome status files The Refreshed entry is the time and date at which the display info was produced its time zone is as per Preferences gt Time zone 2 5 At the bottom are controls to Close the window and see this Help information 12 8 Coordinate Converter Altitude 50 16 20 5 Azimuth fE 207 09 36 1 RA 2000 0 0 1 15 8 Declination 5 08 13 6 Galactic lat f 55 31 49 5 Galactic Ing 100 27 43 7 Ecliptic lat 4 35 12 0 Ecliptic Ing 2 20 14 7 10 16 2001 0 20 53 CDT Close Sky point Get sky Canonize Help This window performs simple conversions among several common astronomical coordinate systems Simply type or paste into any text field and the others will update immediately All fields are in units of Degrees except RA is in Hours Fields may be entered in either sexagesimal or decimal format For example either 10 30 00 or 10 5 Altitude and Azimuth are with respect to the time and location set in the Main window These will change to correspond to the RA and Dec val
32. message then exit install yes no guess whether to install a private colormap prfb print all fallback resources then exit resfile f load alternate resource file f When XEphem is launched it looks for a file named xephemrc in the HOME directory This file is optional If it exists it should contain a line with the following form XEphem PrivateDir xephem The directory named on the right is where XEphem will create and use per user or Private files A leading in the file name can be used to refer to HOME your login directory The example above causes the Private directory to be xephem in the users HOME directory If xephemrc does not exist or does not contain this line the default Private directory is XEphem The private directory will be created if it does not already exist XEphem then also searches for another directory This one can be shared among all XEphem users on a system Files in this directory are never modified by XEphem They include databases of objects supporting images and other files This directory is specified in a resource file named XEphem itself located within the Private directory see above It should contain a line with the following form XEphem ShareDir usr local xephem The directory named on the right is where XEphem will look for all Shared files A leading in the file name can be used to refer to HOME Version 3 5 2 Page 1 5 Introduction Next XEphem sets the in
33. minutes In RA Dec mode this sets Right Ascension and can be varied from 0 to 23 59 40 hours in steps of 20 seconds Version 3 5 2 Page 10 29 Sky View Page 10 30 Version 3 5 2 Solar System View 11 Solar System view Stereo pair Control View Objects Help Tau Tau Perpendicular Ecliptic leg down to Ecliptic plane THT a we u Angle above or 4 CT below Ecliptic O a Plane Parallax er control Orbit 8 21 2001 23 26 12 CDT sun Zoom Rotation This is a graphical representation of the solar system The Sun is always at the center of the screen marked with a small circle 11 1 Mouse controls Any object may be identified by pointing near it and clicking the right mouse button This will bring down a temporary popup menu with additional information until the button is released RA and Dec are displayed as of the time the dot was computed The RA Dec and Mag given for the Earth is that of the Sun Several controls may also be present on the popup menu as follows Persistent Label This toggles whether the label for the object is displayed regardless of whether the View gt Labels option is activated Assign gt To ObjX To ObjY To ObjZ This cascade allows you to assign the given object to become ObjX Y or Z as desired 813 3 This will also cause all other views which are currently making use of this object to be updated and the object will be added to and selected by th
34. of the Main window This will continue until the next Update occurs If you change any field that causes new circumstances the Step value is not added to the current time before the next loop Some graphical views have a push button marked Movie Demo This is a convenient way to start and stop a sample movie sequence If XEphem is currently idle then pushing the button will set the Main window Step to a value that will yield a pleasing motion effect and start looping with a very large number of steps If XEphem is already looping then pushing the button will cause it to stop and set Main window N Steps to 1 The Main window Stop control can also stop the looping in the usual way 1 6 Triad Formats XEphem uses many values that get entered in some variation of the form A B C such as date time longitude and step size XEphem calls this a triad Times and RA are entered and displayed in h m s format If you pick such a time field to change it any of the h m and s components that are not specified are left unchanged from their current value For example 0 5 0 set hours to 0 minutes to 5 seconds to 0 whereas 5 sets minutes to Version 3 5 2 Page 1 11 Introduction 5 but leaves hours and seconds unchanged A negative time is indicated by a minus sign anywhere before the first digit Dates are entered and displayed in any one of month day year year month day or day month year form A Preference selection on the Main menubar an
35. parentheses The second method uses the apparent field of view while looking into an eyepiece and divides this by the magnification which in turn is found from the ratio of focal lengths for the primary mirror and the eyepiece Typical eyepieces provide about 45 degrees apparent fields of view and some premium ones can go to 60 degrees or more After using either method the resulting sky angle can be assigned to the width or height scale for the next eyepiece by using the Set W and H buttons to the right The bottom portion of the Eyepieces window allows you to save your most often used size shape and style combinations When these values are set as desired press Add and they will be added as a new entry to the list A simple name is chosen automatically but of course you can change this to be more meaningful to you Each eyepiece may be deleted or put to use by using the buttons on the left To delete an eyepiece off the Sky View place the cursor near it press and hold the right mouse button slide down and release on Delete eyepiece After at least one eyepiece has been placed in the Sky View a button at the bottom of this window will become available to erase all eyepieces from the Sky View This is permanent If you just want to temporarily turn all Eyepieces off and on use the Eyepieces option in the Control gt Options window Across the bottom are buttons to Close the window and get more information Closing the window has no effe
36. per user Private directory The Filter text field can contain the path and a wild card pattern to match the names of FITS files on your system The default pattern is suitable for most case it filters for any file extension that begins with f and contains a t in any subsequent position When a new Filter is entered click the Filter button at the bottom to apply the pattern to the directory currently chosen 10 4 2 Processing tools Abel l426 Fts 530W 530H The Sky Image Tools window offers several functions with which ee giles Oi to analyze the FITS file showing in the Sky View There are a few Median 36498 StDev 1179 2 sample FITS files included with which to practice using the tools Help Brightness and Contrast Help I Cross section Slice The window is divided into several separate sections each of Help Magnifying Glass which can be opened and closed as desired Please see the Help Help Region of Interest for each section for specific information on each Help 2D Gaussian Measurements Tose Help Always present at the top of the window is a block of basic information about the image This includes file name width and height value and location of brightest pixel value of dimmest pixel mean median and standard deviation of all pixels Two Important Differences between XEphem and FITS 1 XEphem treats the 16 bit image pixels as unsigned values from O through 65535 unlike the FITS standard which spe
37. poles Eyepieces This toggle selects whether eyepieces are drawn on the Sky view if and when any are placed Eyepieces are placed on the Sky view by using the Place eyepiece control in the popup menu activated by the right mouse button The shape and style of eyepieces is defined in the Control gt Eyepieces window 10 3 7 Eyepieces are only drawn if they fit entirely within the Sky View This selection is automatically activated when an eyepiece is placed Magnitude key This toggles whether to display a chart in the lower left corner showing the correspondence between dot size and star magnitude The scale is automatically turned off each time an image is first displayed Auto magnitude When this toggle is active the faintest magnitudes and dot step size will automatically be set to something reasonable based on the field of view This option is automatically turned on whenever the FOV changes for any reason unless it was turned off manually Field Stars This toggles whether field stars are automatically loaded and displayed if the position field of view limiting magnitude or time changes significantly This selection turns itself off if any difficulties ever arise in retrieving field stars See Control gt Field Stars gt Help for more info about field stars 13 4 Page 10 10 Version 3 5 2 Sky View Live dragging This toggle button selects whether the graphics are redrawn in real time as the various scale cont
38. rise transit set times in the Data Table window and the dawn dusk times and the calendar in the Main window refer to UTC or local time Show help tips Yes No whether additional help is available immediately for all selectable buttons and controls using small brief windows near the control Version 3 5 2 Page 2 7 Main Window Confirmations Yes No whether operations which basically can not be undone or which might have irreversible consequences will be preceded with a confirmation window Examples include exiting XEphem or overwriting an existing file Start week on Saturday Sunday Monday sets the day on which weeks begin in the Main calendar Date formats M D Y Y M D D M Y whether dates are shown and entered in month day year year month day or day month year format Fonts displays a window to experiment with fonts while you watch See its own help for details 2 5 2 Colors displays a window to experiment with colors while you watch See its own help for details 2 5 3 Save displays a window which shows how the current functional settings differ from their defaults and allows them to be saved See its own help for details 2 5 1 Page 2 8 Version 3 5 2 Main Window 2 5 1 Save Save Selected Resources e 1 Major resource has been modified since last Save Autoselect Major resources when they get modified Autosave changed Major resources when Quitting Collapse Expand
39. side of the current object The label will consist of the name and or the magnitude depending on which options are selected in the SkyView gt Options Labeling section If neither are selected the label will consist of the name Persistent labels are always on that is they are not subject to magnitude limits options or object type filtering Note this option is maintained separately for trailed objects and for the untrailed objects that is you have independent control over labeling for a trailed object and its currently displayed object since the latter also always appears in the trailed list This can be somewhat confusing for trails which begin Now since in effect the first item is drawn twice once just because it is an object like any other and again as a member of the set of trail history points Track This will toggle object tracking for this object If a trail object is chosen the tracking will apply to the current position of the object See the discussion for the Tracking toggle button for more details 10 3 Trail This toggle is only present if the selected object has a trail defined If it has a trail the toggle state indicates whether the trail is being displayed Note that turning off a trail does not actually discard the trail until the next Update occurs from the Main window Create Trail or Change Trail This pushbutton will bring up a window from which a trail may be defined computed an
40. that are being updated It is recommended that you keep any special work you may have done in this directory then remove it letting the install script create a fresh directory Manual page the directory where the XEphem manual page will be placed It is written for chapter 1X Executables the directory where the xephem program itself will be placed and a few other supporting programs Private each user of XEphem can have a directory for their private files An initial sample is set up in this directory 3 The Base Installation directory requires about 200MB If there is not that much on the specified directory the script will now exit 4 Next you must indicate your operating system and architecture If you chose one from those listed the proper executable files will be copied to the Executables directory If you elect to not specify all supporting files will be copied but you will not have the xephem program itself In this case some hints on how to proceed are in the README on the CDROM 5 Next you will be asked if you want to load the USNO SA2 0 catalog This requires an additional 600MB in the Base Installation directory You are not asked if this directory does not contain this much room You may not want this catalog even if you have room It is a list of about 55 million stars specially chosen to be roughly evenly spaced on a grid Page 1 4 Version 3 5 2 Introduction around the entire sky for use as astrometric referenc
41. that article you can see that the elements shipped with XEphem for 241 Germania no longer quite match the epoch of the image and the Saguaro Astro Club entry for M21 is slightly too far south and east This emphasizes an important note XEphem is only as good as its databases 2 7 4 Displaying images This example will go through displaying an image in the Sky View The image may be either a FITS file on your local disk or may be retrieved via the Internet Bring up the Sky View display Main gt View gt Sky View Bring up the Image control window Sky View gt Image gt Load and Save To display a FITS file use the file selection window at the bottom to browse your local file system When the you have found the file select it in the list and press the Open button The image will be displayed in the Sky View Note In order to be displayable by XEphem the FITS file must be in 16 bit image format BITPIX 16 Version 3 5 2 Page 2 19 Main Window Or to retrieve a Digitized Sky Survey image use the Sky View scales to center the view on the desired sky location set the field of view scale as desired select either of the buttons at the top labeled STScl or the ESO the click Get For these to work you must have a live Internet connection STScl is located in Maryland USA ESO is in Germany They both provide identical service so use whichever gives you better network performance The maximum size of an image retrieved in
42. the additional information window if present from the screen 6 3 2 3 View menu Top view Selects whether to also display another window looking down on the Mars system from above the N celestial pole This window will tend to remain aligned above the main view when either is resized Moons are displayed only if they are in sun light Sky background Selects whether to also show objects within the current field of view that are in the XEphem database memory or available from the Field Star facility The size of the object is determined by the limiting magnitude as specified by the scale at the right Objects are drawn using the same symbols as used by the Sky view While this option is on XEphem will continue to retrieve field stars as required Bright moons If this option is in effect then the diameter of all moons will be increased by 3 pixels This option also insures that even those moons which are dimmer than the limiting magnitude as specified by the scale to the right will be drawn with a circle of diameter 3 pixels Tags Search whether to show the Roman numeral designation beneath each moon and a 1 arc minute scale calibration line Flip T B Flip L R These allow the scene to be flipped vertically and horizontally respectively Version 3 5 2 Page 6 5 Mars View 6 3 2 4 More info dialog Under Cursor Latitude N 21 52 Longitude 114 08 Sub Earth Lat N 24 09 Central M Long A 74 44 Seeing arc s
43. the algorithm will immediately reject the entire group if even one pixel is higher than this The idea here is that if a star is so bright as to be even a little burned out its centroided position is likely to be worse than not using it at all If you feel otherwise set this to 65535 and no groups will be rejected at least for this reason S N ratio This parameter sets the minimum signal to noise ratio of a candidate star The algorithm breaks an image into several smaller regions and computes several statistics of all the pixels in that region In order for a group of pixels to be considered a star its brightest pixel must be at least the median plus this parameter multiplied by the standard deviation computed from the statistics of the region in which it is located Basically the larger this number the more distinct the star must be Row 7 Setting realistic search goals The bottom row contains two parameters that effect the goal of the search algorithm Max pix acc This parameter tells the search algorithm not to expect position information for the star like artifacts extracted from an image to be any better than this fraction of a pixel Min pix acc This is the worst pixel distance acceptable between each image star and its closest catalog star Version 3 5 2 Page 10 25 Sky View Close Closes this window Commences the search for a solution using the image currently in the Sky View and the parameters in the various fie
44. the sun and the earth The other the luminosity index k characterizes the brightness change of the object as a function of its distance from the sun This is generally zero or very small for inactive objects like asteroids The model may be expressed as m g 5 log10 D 2 5 k log10 r where m resulting visual magnitude g absolute visual magnitude D comet earth distance in AU k luminosity index and r comet sun distance Note that this model does nottake into account the phase angle of sunlight 13 3 4 Parabolic objects Parabolic objects are characterized by 9 parameters the parameters that define a heliocentric parabolic orbit and the magnitude model coefficients These orbital parameters are in order T epoch of perihelion i inclination degrees o argument of perihelion degrees q perihelion distance AU O longitude of ascending node degrees D the equinox year i e time of i O o Page 13 10 Version 3 5 2 Data g k two fields for the magnitude model s angular size at 1 AU arc seconds optional The g k magnitude model requires two parameters to be specified One the absolute magnitude g is the visual magnitude of the object if it were one AU from both the sun and the earth The other the luminosity index k characterizes the brightness change of the object as a function of its distance from the sun This is generally zero or very small for inactive objects like asteroi
45. they are not pickable and names are not drawn Also while each trailed location is accurately marked on the display because of diurnal motion these trails are not useful for comparison with the background of fixed stars Use the RA Dec mode for that This is so important and easily overlooked that you will see a reminder notice to this effect the first and only time you create and display a trail in Alt Az mode Finally be sure to recompute any trails if you change any of the preferences or circumstances in the Main menu 10 9 Scale controls FOV The vertical scale on the left side sets the vertical field of view of the display The horizontal field of view is determined by the width of the window at the same scale The FOV can be varied in 5 minute increments from 0 05 through 180 degrees The buttons below present a quick way to set the scale to exactly 90 degrees and to resize the window by changing the width to 1 1 and 2 1 W H aspect ratios Alt Dec The vertical scale on the right side sets either the center altitude or declination depending on the display mode The value can be varied from 90 to 90 in increments of 5 minutes The buttons below presents a quick way to center the scale at exactly 45 O or 45 degrees Az RA The horizontal scale across the bottom sets either the center azimuth or RA depending on the display mode In Alt Az mode this sets azimuth and can be varied from 0 to 359 55 degrees in steps of 5
46. 1 Moon Positions Jupiter radii 13 463 2 641 10 752 0 539 III Ganymede 1 IVY Callisto 1 Tag Name ES Jupiter 1 1 0 000 0 000 I_ To 11 3 655 0 354 II Europa 1 1 4 619 1 150 1 1 x GE Y GS Z front 0 000 4 657 8 063 6 044 24 235 RA 4 22 09 22 4 22 03 31 4 22 01 75 4 21 47 45 4 22 26 61 11 20 2000 7 56 07 UTC Close Sys 20 20 20 20 20 II 73 915 Dec 35 34 9 35 26 3 35 07 0 34 30 9 35 48 0 Mag 2 9 This button brings up a separate window which contains quantitative information about Jupiter s moons and central meridian longitude All values may be used in plotting listing and solving The E and S columns are 1 if the moon is visible from the Earth and Sun respectively The locations of the moons are given in two coordinate systems The first three columns are the displacements of the moons in Jupiter radii with respect to the celestial plane The next two columns give the RA and Dec location of the moons in the current equinox as specified on the Main window Value of the System II longitude of the Great Red Spot is displayed The value may be changed according to current information Pressing Enter will update the Jupiter display with the new value Version 3 5 2 Page 7 3 Jupiter View Page 7 4 Version 3 5 2 Saturn View 8 Saturn view Pole View Sunlight gt terminator IV p Orientation w ll l vb Earth Control View Help A z Ea
47. 1 13 1 Load and Delete yeri 32 2 A a ERE ale Bas 13 1 13 1 1 Controlmenu 2222 css E n E E KA E nennen nenn 13 2 13 1 2 edb File format 2 2 222 con nnenne nennen nennen 13 3 13 13 Not cua REED ee Beh 13 5 13 2 Download Internet files zunsenenen nennen nennen nenn 13 5 13 3 Search Ob X Vi Zoila leet eed ae 13 6 13 3 1 Fixed ODjOCIS sa avd acer Gene ee BR de kt 13 8 13 3 2 Elliptical objects 2 ete 13 8 13 3 3 Hyperbole Objects cirios rr ee Red a ab whee a ae 13 10 13 3 4 Parabolic objects 2 0 eee 13 10 13 39 59 Earth Satellites iia roza ren ee ag 13 11 Version 3 5 2 Page i iii 13 4 Field Stai S iia sae ei we aa nee 13 11 14 PIE A cane eee eer eee ieee ke we a at 14 1 5 WANS science kata AAA A EA a 15 1 16 Meade LX200 Support 2 00 cece eee 16 1 16 17 Disclaimer 2 cio a do ING Ic eee Bein 16 1 16 2 Cable 2 2223 vata eis 16 1 16 3 Routine operation 00 cece nun nn nennen nenn 16 1 1 NOOO aa na er een 17 1 18 Gredils 22 2 0 u a na AA A a a esta 18 1 TOMADOUL ri 19 1 Page i iv Version 3 5 2 Introduction 1 XEphem the Interactive Ephemeris STA XEphem is an interactive astronomical ephemeris program XEphem provides a rich set of accurate astrometric calculations and attractive graphical and image displays in an easy to use GUI framework XEphem includes extensive on line context sensitive help examples and bubble tips on all controls Thank y
48. 3 RISK 16 1 Roaming 10 3 roaming 10 22 ROI 10 4 10 23 RS232 16 1 Running 10 27 S N ratio 10 25 satellite 13 5 satellites 13 11 Saturday 2 8 Saturn view 8 1 Save 2 9 2 10 Scale controls 10 29 Scales 11 4 Scripts 13 5 Search 13 6 seeing 6 3 Select fields 12 1 Serial device 10 27 SETI 12 11 SETI home 12 11 setting 3 3 setup exe 1 6 SGP4 5 1 Shared 13 1 sharing 1 6 Sharper 10 21 Show plot file 12 2 Sidereal 2 2 SIMPLE 10 19 Site 2 3 Sites 2 13 Sky Point 12 7 12 11 Sky point 12 12 Sky Point 13 7 Sky view 2 15 10 1 Sky View marker 10 27 SOCKS 2 5 Solar System 11 1 Solar System view 11 1 Solve equation 12 4 Solving 3 5 Sort 10 14 Space Station 2 26 Spacecraft 4 3 Spherical 5 5 spherical 5 5 standard deviation 10 20 star like artifacts 10 25 Start 15 2 Std Dev 10 21 Step 1 10 Stereo 11 2 STScl 2 20 SubLat 5 4 subsolar 4 4 Sun Dip 2 3 Page I 3 Index Sunday 2 8 xephem exe 1 8 Sunlight 5 6 xephem ico 1 9 Sunrise 2 20 xephemdbd 13 12 System log 2 4 xephem_db fifo 13 2 xewinregister 1 6 taskbar 1 7 TCP IP 2 5 Zenith 3 2 telephone 16 1 Zoom 10 5 Telescope 10 3 10 26 Zoom Back 10 4 Temperature 2 2 Zoom In 10 4 tick mark 15 1 tick marks 15 2 13 7 tilt 8 4 time interval 15 1 12 2 time zone 3 4 14 1 Times 1 11 title 12 2 TODAY 3 4 TODO 17 1 tonight 2 14 Toolbars 10 2 Top view 6 5 7 2 8 3 9 2 Topocentric 2 7 3 5 Topocentric apparent place 12 1 Track 10
49. 6 Tracking 10 7 trail 2 17 Trail 10 6 Trails 10 29 trails 11 2 Trails 11 3 15 1 transitting 3 3 Triad 1 11 TT 2 2 Tycho 13 14 TZ 2 2 Umbra 4 3 Uninstallation 1 10 UNIX 1 3 Uranus view 9 1 USB 1 10 Use field 10 25 USNO 13 13 UT1 2 2 UTC 2 2 3 4 watch 10 19 WCS 10 24 WCS Solver 10 24 Weather map 5 5 week 2 8 Whole day 15 2 Whole interval 15 2 Whole min 15 2 Wide 10 21 Windows 1 6 Windows Filenaming 1 9 Windows Printing 1 9 Workspace 1 7 XEGAMMA 10 22 XEHIGLUT 10 22 XELOGLUT 10 21 XEphem 1 1 Page l 4 Version 3 5 2
50. 6 Version 3 5 2 Main Window Configure Field stars sets up how and whether to read several very large databases of faint stars which XEphem refers to as field stars including the Hubble GSC USNO Hipparcos Tycho and PPM catalogs 2 5 Preferences menu The Preferences pulldown lists the available preferences that may be changed at run time Whenever any are changed all effected fields are immediately recalculated and redisplayed throughout XEphem The preference include Equatorial Topocentric Geocentric controls whether the RA and Dec values displayed throughout XEphem are for the current local surface location topocentric or from the center of the Earth Alt Az values are of course always topocentric Precision Hi Low controls how much precision is shown for most angles This is a change in display format only and does NOT imply a change in accuracy Log Bell On Off whether to ring the bell each time a new message is added to the System Log window The System Log window is accessible via the File menu in the Main menu bar Prompt Prefill Yes No whether prompt strings from the Main window and Search windows are filled with the current value or blanked out This is also handy to allow copy paste of these values Units English Metric whether local topocentric circumstances are given in English or Metric units of measure Time zone UTC Local whether the time stamp below each major view the
51. 617 3 544 15 12 409 1 678 20 2 066 4 485 2 11 20 2000 16 Close X GE GS zZ front 000 917 724 754 991 261 21 21 21 21 21 21 193 19 19 19 19 19 56 07 UTC 18 17 18 17 16 18 31 91 02 37 36 08 16 6 16 16 16 16 Dec 21 21 21 21 21 215 35 27 49 241 32 28 3 1 3 3 1 Mag 5 8 14 2 14 8 13 7 14 0 16 3 This button brings up a separate dialog which contains quantitative information about Uranus s moons All values may be used in plotting listing and solving The E and S columns are 1 if the moon is visible from the Earth and Sun respectively The locations of the moons are given in two coordinate systems The first three columns are the displacements of the moons in Uranus radii with respect to the celestial plane The next two columns give the RA and Dec location of the moons in the current equinox as specified on the Main menu Version 3 5 2 Page 9 3 Uranus View Page 9 4 Version 3 5 2 Sky View 10 Sky view A display and Fast object Telescope Favore Toobar for General processing locate configuration sels 0 displayed options and control settings Isplaye Coordinate grid Control Images Locate Telescope History Help Field of Fire ES AT Tai Toolbar for View Halte ae Measurement Control wu tools Open Fr y Cluster
52. 9 Mark 10 24 Mark stars 10 26 Mars view 6 1 Maryland 2 20 Meade 16 1 mean 10 20 median 10 20 meridian 3 2 Metric 2 7 Microimages 1 6 Minor resources 2 9 Mira 12 10 MKS 1 6 Monday 2 8 Moon view 4 1 Movie Demo 1 11 4 3 5 3 6 4 7 2 8 2 9 2 11 2 Version 3 5 2 Multiple Users 1 8 N Steps 1 11 2 3 Narrow 10 21 Network setup 2 5 New 10 24 New Moon 2 4 Night ata Glance 12 9 No Dups 13 2 no hardware mode 10 27 Nominal 10 21 Now 2 4 nutation 12 1 Nutc 1 8 Obj X 13 6 Objects 13 1 ObjX 3 1 ObjX Y Z 13 6 occultation 2 25 orbit decay 13 5 13 11 Orientation 10 9 15 1 OSX 1 10 Overview 1 7 pairs 12 7 parabolic 13 5 Parabolic 13 10 Parabolic objects parameters 13 10 parallax 10 3 12 1 Path left 15 1 Path right 15 1 pattern matching 10 24 Pause 1 11 Penumbra 4 3 perihelion 13 4 13 10 Persistent Label 10 6 persistent label 10 12 perturbations 12 1 Photom ref 10 5 Planets 5 1 planets 11 2 plot 2 20 Plot 12 1 Plot values 12 1 Popup 5 4 POSIX 2 14 Postscript 1 9 14 1 power 10 22 PPM 13 14 precession 3 1 3 4 12 1 Pressure 2 2 Print 14 1 Printing 1 9 Private 13 1 profile file format 10 14 Proper Motion 13 13 Proxy 2 5 RA 2 7 3 2 RA of ascending node 13 11 Range 5 4 Reference Mag 10 24 refraction 3 3 12 1 Refresh 2 10 12 12 Version 3 5 2 Index Region of Interest 10 4 Region of interest 10 23 Resources 2 9 Reverse 10 21 Ring 2 22 rings 8 1 rising 3
53. 9 2 which to zoom in upon Help Brightness and Contrast Help Cross section Slice El This section may also be opened by the right toolbar button Help O Magnifying Glass that looks like the curson has just drawn a box around a Help M Region of Interest galaxy Diag 20 0 WxH 1 20 Cursor 46847 at 280 367 Max 46847 at 280 367 The following statistics about the image pixels in the ROI are en ren er shown In the table Help 2D Gaussian Measurements x Close Help Length of the diagonal Width and height of the region Value and location of the cursor as you draw the ROI Value and location of the largest pixel in the ROI Value of the minimum pixel Mean value of all glass pixels Median value of all glass pixels One Standard Deviation of the pixel values about the mean 10 4 2 5 2D Gaussian Measurements This section is based on results of modeling stars with a 2 en dimensional Gaussian The model finds the coefficients in the ME a ae aa following function of pixel coordinates x and y that minimizes the Median 36498 StDev 1179 2 squared error with each pixel in an area Help Brightness and Contrast Help Cross section Slice g x y B A exp 0 5 sqr x mx sx sqr y my sy Help Magnifying Glass Help Region of Interest where Help 2D Gaussian Measurements mx is the row coordinate from some reference position Reference Mag 13 1 New Mark my is the same for a column Mag 14 97 0 37 i sya X 401 4 RA 3 19 21 94
54. Almanac The g k magnitude model requires two parameters to be specified One the absolute magnitude g is the visual magnitude of the object if it were one AU from both the sun and the earth The other the luminosity index k characterizes the brightness change of the object as a function of its distance from the sun This is generally zero or very small for inactive objects like asteroids The model may be expressed as m g 5 log10 D 2 5 k log10 r where m resulting visual magnitude g absolute visual magnitude D comet earth distance in AU k luminosity index and r comet sun distance Note that this model does not take into account the phase angle of sunlight When using this model for elliptical objects the first of the two magnitude fields must be preceded by a letter g This applies in both the edb database file and the corresponding menu elliptical object definition prompt otherwise the default magnitude model for elliptical objects is the H G model The H G model also requires two parameters The first H is the magnitude of the object when one AU from the sun and the earth The other G attempts to model the reflection characteristics of a passive surface such as an asteroid The model may be expressed with the following code fragment beta acos rp rp rho rho rsn rsn 2 rp rho psi_t exp log tan beta 2 0 0 63 Psi_1 exp 3 33 psi_t psi_t exp log tan beta 2 0 1 22
55. Bayer Toolbar Sl designation for How things are displayed IL ol Sy i be Dec A e S or Alt z eo LA control Galactic Plane Ecliptic Stellar Flamsteed ddr 7 number FOV NGC 2264 DD MM Center Dec or Az FOV 28 05 RA 7 03 50 Dec 20 11 30H 1 1 2 1 10 15 2997 0 57 04 CDT 45 00 0 00 45 00 Fast ae IS Fast FOV 90 E Dec or Alt Fast Square or Center RA Date and Time RA or Az 45 0 or 45 Rectangular Window or Az of Display control This window presents a schematic representation of the sky showing database objects and useful auxiliary information A FITS file image can also be displayed simultaneously The dominant center area displays each object that meets the brightness and type filter selection criteria A menu bar across the top offers access to all functions Fast access to certain functions are available from the surrounding toolbars The mouse buttons can be used inside the display area for additional functionality specific to the exact location of the cursor when clicked Complete details on each control are found in the specific Help choices Note that while looping with Pause set to 0 the Sky View is not updated although all quantitative information is always updated internally each step This is to permit creating plots and using other XEphem features that use many time increments to run much more quickly if the Sky View is unmanaged or with Pause set to 0 Version 3 5 2 Page 10 1 Sky View 10 1
56. Center and the Smithsonian Astrophysical Observatory for the SAO star catalogue Thanks to the members of the Saguaro Astronomy Club for the preparation and free distribution of their deep sky database Any errors in conversion to the edb format are strictly mine Thanks to Chris Beecroft lt aldebaransys home com gt for his encouragement and technical assistance in adding postscript The limited results in no way reflect on his capabilities Initial encouragement was also received from Frank M Siegert lt frank miranda tue schwaben de gt And thanks to everyone who has asked for printing over the years now admit that like it too Bright stars are based on the 5th Revised edition of the Yale Bright Star Catalog 1991 from ftp adc gsfc nasa gov pub adc archives catalogs 5 5050 Common names supplied by Robert Tidd inp violet berkeley edu and Alan Paeth awpaeth watcgl waterloo edu Any errors in conversion to the edb format are strictly mine wish to thank all the organizations behind the incredible Internet for its maintenance and free and easy access also wish to express my hope that it retains the spirit of cordial cooperation it fostered in its formative years learned most of what know of X Windows and Motif programming from ICS courses and material found in the various excellent texts from O Reilly amp Associates Inc Thanks to MIT and the X Consortium for inventing championing and maintaining the X W
57. Directories 1 es directories 034746806 fts 1302 8152 xf it fts Current directory 02 8152 fts and file pattern Name of fil Frmi22c5 wcs fts Scolled list of files matching Frmi22c5 fts Filter in this directory to load Es ection home ecdowney xephem Abe11426 fts Apply Filter again Load the named A file now IT Pen Filter Close Help This window allows you to display a FITS file in the Sky View window You may display local files or download the Digital Sky Survey directly from the Internet The image is resized to match the size ofthe Sky View window Once an image is displayed all graphical features of the Sky View are available such as grids and labeling objects loaded in the XEphem database Most of these features require that WCS headers be present in the image XEphem can help create these using the Images gt WCS Solver tool This window contains several sections Each is described below Also notice the tiny square box just to the lower right of the FITS Header box This is a pane control with which you may adjust the proportion of window real estate used by the FITS box Of course you can also increase the total size of the window as well Get This button heads up the section for downloading images from the Net You may choose DSS generations 1 and 2 and either Red or Blue filters for the latter Page 10 18 Version 3 5 2 Sky View The DSS is maintained by the Sp
58. Filter field to be rescanned for all files which match the filter pattern therein Double click on a directory to show the files which match the pattern A database file is loaded into memory by selecting the file name in the list at right then pressing Load at the bottom of the window or by double clicking its name in the list Both edb and tle formatted files are supported If the file is already loaded it will first be deleted If the file contains exactly one entry the object may also be automatically assigned to a user defined object see Help gt on Control for more details Or rather than browsing any file name may be simply explicitly typed in the Selection field and loaded by typing Enter or pressing Load The sash in the center of the window controls the proportion of space allocated to the Catalogs and Browse sections as desired XEphem may also load objects from another process via a fifo Please refer to the separate description of this facility in Help gt on Control 13 1 1 13 1 1 Control menu Delete all Deletes all file and their objects from memory The files on disk are not effected Open DB Fifo Listen for database objects arriving via a fifo from another process XEphem attempts to reopen the fifo each time the button is pressed The file name of this fifo is fifos xephem_db_fifo off the shared directory All relevant displays are automatically updated when data arrives via this fifo The format of the fifo d
59. If you have installed ghostscript for printing then also remove these two programs AFPL Ghostscript 7 00 AFPL Ghostscript Fonts During these uninstalls a few files will not be successfully removed for various reasons This is normal After running each uninstall as above use Windows Explorer to remove the directory in which XEphem was originally installed the default was c program files clear sky institute inc Similarly remove the X server directory the default for which was c program files microimages This will catch these few stray files and XEphem and its helpers will be completely gone 1 4 Apple Mac OS X Installation Details arrived too late to be including in the first printing Please see the appendix 1 4 1 LX200 Apple computers usually have USB ports not serial ports To operate an LX200 with its serial port we suggest the USB Serial adaptors made by Keyspan see http www keyspan com You will need an adaptor such as the model USA 18x one port or USA 28x two ports and their driver software for Mac OS X Only one serial port is necessary for the LX200 but an extra might be handy for other things Follow Keyspan s installation directions After a successful installion the serial devices will be available in dev for example dev cu KeyUSA28X9131 The exact name for your LX200 connection will vary depending on your USB configuration Whatever it is inform XEphem as follows 1 From the Main XEphem window
60. N Steps gt 1000000 Main gt Update The looping stops at Aug 10 1995 at about 19 24 UT The August 1995 Sky and Tel page 72 says it occurs at about 21h 2 2 7 7 Lunar occultation This example was taken from the lunar occultation of Spica Alpha Vir which occurred January 23 1995 UTC as reported in Sky and Telescope January 1995 If the YBS edb database is not already loaded load it now so that Spica is loaded in the XEphem database Main gt Data gt Load Delete YBS edb Append Control gt Close Set UTC Zone preferences Main gt Preferences gt Time zone gt UTC Set the Topocentric Equatorial preference Main gt Preferences gt Equatorial gt Topocentric Set Equinox to EOD occultations must always be computed using EOD Main Equinox select EOD Set up the date and time to Jan 23 1995 11 45 00 UT using the calendar and the UTC Time selections in the Main window Set the Step size to one minute 0 1 0 using the Step selection in the Main window Set the location to Chicago using the Site selections in the Main window Main gt lt Site gt type chicago into the Search field type Enter type Set select Close or scroll down to Chicago Illinois and double click on it Version 3 5 2 Page 2 25 Main Window Main gt Update Display the Moon Main gt View gt Moon Make sure the true Sky background option is enabled Moon gt View gt Sky background Spica is just behind the dark western li
61. Network setup displays a window offering choices for how XEphem accesses the Internet 82 1 1 External file drives XEphem from a file containing times and latitude longitude locations See its own help for details 2 1 2 Progress Meter displays a simple bar graph of XEphem progress The accuracy and usefulness of the display are highly problematic at this time Forward 1 Step causes Time to be changed by one Step value This action can also be performed when the cursor is over any XEphem window by typing Control f Invoking this command also stops looping if it is running Backward 1 Step causes Time to be changed by the negative of one Step value This action can also be performed when the cursor is over any XEphem window by typing Control b Invoking this command also stops looping if it is running Update performs the same action as the Update button across the bottom of the Main window This can also be performed by typing Control u in any XEphem window Page 2 4 Version 3 5 2 Main Window Quit exits XEphem If any resources have been modified and Preferences gt Confirmations is On a reminder will first appear and allow you to bring up the Save window if desired This can also be performed by typing Control d in any XEphem window 2 1 1 Network setup Network setup Direct connect via SOCKS 1080 x y com via Proxy 000 fa b com Auth Name Password Ok Close Help This wi
62. ORAD documentation spacetrk pdf Improvements to Delta T code help and wording contributed by Neal McBurnett nealmcb bell labs com Any parts of the USNO SA2 0 catalog that are included with XEphem distributions are done so with the following understandings It may not be the latest version check with http ad usno navy mil If you paid for XEphem you paid for the software not this catalog The catalog is available free from the USNO Inclusion of the SA2 0 catalog does not imply an endorsement of XEphem by USNO nor did have privileged access to the catalog nor does the US Government affirm or guarantee that XEphem works properly in any way Thanks to Atsuo Ohki ohki gssm otsuka tsukuba ac jp for numerous fixes and features Thanks to Robert Lane roblane alum mit edu for Uranonmetria 2000 work The near real time weather map in the Earth view is provided by the Space Science and Engineering Center at the University of Wisconsin See their web site at http Awww ssec wisc edu ssec html The XEphem logo was contributed by Jonathan Adams jfadams mail arc nasa gov The galaxy background image is from Galaxy Photography www galaxyphoto com For the years 1999 2010 the natural satellite ephemerides for Mars Jupiter Saturn and Uranus are based on developments in mixed functions computed and contributed at Bureau Des Longitudes http www bdl fr by J E Arlot Ch Ruatti and W Thuillot Many thanks The authors state th
63. Ok place cursor over the central dot Hermione and press button 3 Create Trail Orientation Left Interval 1 Day Label Every 2 Format Date Font Small Number of tick marks slide to 8 Ok center the trail by placing cursor near dot for 7 28 95 and press button 3 then scroll down and release on Center add nearby Hubble Guide Star Catalog entries If you have not already done so set up the source for the GSC stars Sky View gt Control gt Field Stars Enable viewing Field Stars and load an initial set Sky View gt Control gt Options gt Field Stars The GSC stars will now be read in and displayed if desired overlay with a coordinate grid Sky View gt Control gt Options gt Grid making the Sky View wider will allow room for more grid labels Page 2 18 Version 3 5 2 Main Window Control Locate Telescope History Help ot sgl a S bei g N N Ss E 72471995 al 21 Hermione ER Es i p 261199 gt tt E i o SE mn 10 8 89 21 10 00 N es i J L FOV 1 23W x 1 15H RA 22 27 54 Dec 20 37 SoH 1 1 2 1 7 24 1995 0 00 00 UTC 45 00 0 00 45 00 As another example investigate the appulse between M21 and 241 Germania near July 15 1995 Use ObjY for the asteroid so you can leave ObjX as Hermione If you have your Sky amp Tel handy this is also described on the same page as the above reference From the picture in
64. Toolbars The toolbars are divided into three broad categories Down the left are choices that effect How the scene is portrayed such as coordinate system flipping and magnitude limits One magnitude deeper One magnitude shallower EY Automatic magnitude A Monument view images only 8 Brightness and contrast images only RA Dec or Alt Az display coordinates graphics only images are always RA Dec Spherical projection graphics only imags are always spherical Rectangular projection graphics only images are always spherical von Flip left and right Flip up and down How Across the top the choices effect What is displayed such as coordinate grids local horizon and the classes of celestial objects HE Qe we Vega se a O ES a a y ee what Display field stars Display any stars Display nebulae Display galaxies Display clusters Display solar system objects Display coordinate planes Display stellar magnitude scale Display star names Display constellations Display horizon profile 1 subject to settings in Control gt Filter Display coordinate grid 2 subject to settings in Control gt Options 3 matching display mode when turning On All of the buttons in the Left and Top toolbars are just convenient shortcuts to functions that can also be accessed from the Options and Filter windows available in the Sky View Control menu Please read the help for more
65. Tools size that bounds the solution You can use the plotting feature to study a function and get an idea of the solution then use the solver feature to zero in Page 12 6 Version 3 5 2 Tools 12 4 Find close pairs Control Options Help Max Sep degs B o Mag limit 20 0 Found 3313 Topocentric Pairs lt 2 00 00 13 88 171 Ophelia 15 55 857 Glasenapp 0 01 30 5 34 Leo 53 17 32 1607 Mavis 0302317 4 12 Vir Omicron 9 15 90 791 Ani 0302335 13 80 NGC 4006 16 83 916 America 0302350 15 50 NGC 3776 14 72 774 Armor 0303339 14 50 NGC 5130 13 81 337 Devosa 0303340 19 99 NGC 3345 15 74 1089 Tama 0303350 5 82 Gem 52 11 62 128 Nemesis 0303358 4 01 Sco Nu 14 14 49 167 Urda 0305321 6 30 Sco Nu 14 14 49 167 Urda 0 05 58 14 00 NGC 2720 15 33 226 Weringia 0 06 09 15 37 635 Yundtia 16 50 1664 Felix 0307302 14 00 NGC 3357 15 75 4820 Fay 0 07 31 14 50 NGC 3580 14 17 212 Medea 0 07 38 5 64 Lib Zetal 32 15 14 858 El Djezai 0308303 15 18 462 Eriphyla 16 62 1171 Rusthawe 0308304 13 50 NGC 3032 13 66 328 Gudrun 0 08 24 15 29 317 Roxane 15 12 358 Apollonia 0 08 24 13 90 NGC 5705 19 77 3103 Eger 0 08 43 14 00 NGC 2794 14 59 112 Iphigenia 0 09 00 13 40 25 Phocaea 17 30 12008 1996 TY 0 09 21 11 28 2000 19 25 07 UTC This window allows you to scan the list of objects currently in memory for all pairs which are separated by less than a given angular distance First set up the desired maximum separation in degrees and faintest magnitude
66. Update to start running This is so common in fact the handy shortcut button to the right of the Looping title labeled Now performs exactly these steps The value set for Pause will be used unless it is 0 in which case XEphem sets itto 10 seconds Speaking of shortcuts the 1 and 1 buttons to the left of the Looping label each subtract or add to time by one Step regardless of the setting for N Steps The value of N is updated accordingly These two actions can also be performed from the keyboard by typing Control b backward and Control f forward Note that when looping with Pause set to 0 most numeric field data are not drawn in order to speed up the display These values are always updated internally however and may safely be used for plotting solving or listing This is true even if the window that displays the information is closed Most fields on the Main window may be changed by clicking them A prompt window with a brief explanation of the field will appear A new value may be typed into the text field provided If Ok is clicked the new value will be used if Cancel is clicked the field will be left unchanged In either case the prompt window goes away Some of the windows have an extra button which offers a handy way to enter frequently used values for the field If you change a field on the Main window that would invalidate any of the other fields in any XEphem window the message NEW CIRCUMSTANCES flashes near the top
67. Uranus Neptune Size SnDst Set z Neptune Pluto VMag SnLght Hrsup Pluto MISS ZARYA Phase Elong Iss ZARYA Ok Apply Close Help Version 3 5 2 Page 3 1 Data Table This window lets you configure which rows and columns will be in the Data Table When this window first comes up it will be set to indicate the state of the Data Table You may then manipulate the toggle buttons as desired To actually change the Data Table to a new configuration select the Apply button Ok does the same thing but also closes this window Close just closes this window without making any permanent changes In addition to manipulating each item individually each columns includes handy shortcut controls at the top to make changes to column as a whole The first column of this window selects which rows will be present in the Data Table The planets and the Sun and Moon are always in this column If user defined objects ObjX Y or Z are defined then they will also be present and controllable from this column See the help for the Set ObjXYZ window for more information about user defined objects 13 3 Entries in the remaining three columns in this window control which columns will be present in the Data Table They are grouped into three categories for convenience Column two controls miscellaneous basic information The descriptions of each entry are as follows Cns name of the constellation in which the object appears RA Right ascension if Main
68. Version 3 5 2 Solar System View Close This push button will close both the main Solar system view and the Stereo view If the Solar System view is closed while the Stereo window is on it will reappear when the Solar System window is reactivated 11 3 View menu Trails This toggles whether trails if currently defined are displayed for the basic planet objects and the three user defined objects if any The trails may be turned on and off as desired without loss but the trails are permanently discarded at the next Update from the Main window Ecliptic This toggle button controls the display of a set of circles in the ecliptic plane spaced at regular intervals The interval between each circle is displayed at the upper left of the view Labels This option causes each object s name to appear Basic Legs This toggle button controls whether a line is drawn from each planet and any ObjxYZ user objects to the ecliptic This aids in visualizing the 3D location of the objects DB Legs This toggle button controls whether a line is drawn from each Database object other than planets and user ObjXYZ objects to the ecliptic This aids in visualizing the 3D location of the objects 11 4 Objects menu The planets and the user defined objects ObjX Y and Z if they are solar system objects may be individually turned on and off without loss of any trail data associated with them by using the toggle buttons in this Objects pu
69. Window one step my double clicking on a site name in the list If Set is pressed and the text field does not exactly match any entry in the list the Name field in the Main Window is simply set the string without effecting the other fields The text field may also contain a search pattern Type Enter or activate the Search button to scroll the list to the next item which contains the text ignoring case punctuation and spaces Calendar The calendar on the right of the Main window is based on local time or UTC depending upon the Time Zone preference Selecting a date button will set the date Buttons before the first of the month and after the last of the month work as expected that is they also imply a change in month or year as necessary The month and year buttons pop up selections that allow these to be changed as well At the bottom are buttons to set the time and date to the computer clock or move backwards or forwards by one day or week Except for Now using the calendar does not change the current time just the date New and Full Moons are marked on the day on which they occur in the selected time zone 2 1 File menu The File pulldown contains a few miscellaneous controls System log displays a scrolled list of informational messages XEphem may beep whenever a new message is added depending on the Log Bell preference see below Messages appearing immediately in attention boxes are also logged here for reference
70. XEphem eks i fem The Scientific Grade Interactive Cross Platform Astronomical Software Ephemeris UNIX Mac OS X MS Windows Version 3 5 2 User Manual elear Sky Institute Copyright O 2002 Clear Sky Institute Inc All rights reserved www ClearSkyInstitute com This document prepared on Linux kernel version 2 4 9 13 with Applixware version 4 4 2 Last changed January 14 2002 Contents 1 XEphem the Interactive Ephemeris 000 eee eens 1 1 1 1 Summary of Capabilities 0 0 0 ee 1 1 1 2 UNDG Installation 2 5 cios chia 222 se bee eds an 1 3 1 2 1 Launching XEphem 0 a E EEE nennen nenn 1 5 1 3 Windows Installation Huren nennen nennen en 1 6 1 3 1 Starting XEphem the First TiMe ocooococccoccoccnc 1 6 1 32 File Structure 2 2 Ba wen 1 7 1 3 3 Multiple Users ran er nei eb 1 8 1 3 4 Fie namni see 2 eae eo eb een 1 9 TS Oe MINING Me esse en a Hei pokey een bared Rod aa 1 9 1 3 6 Uninstallation ota 26a ete an el 1 10 1 4 Apple Mac OS X Installation 2 0 0 0 000 cee 1 10 o A a leicht ath dette een 1 10 15 JOPerationy o ee ee Bone Mate te aes 1 10 1 6 Thad Formats 22 2 a er HR I a ee ai 1 11 2 Main WINGOW souvenir in 2 1 2 1 File Menus ci ia 2 4 2 1 1 Network Setup woe esi ae Pa ae ak eben 2 5 2 1 2 External Time Loc 222er 2 5 2 2 VIEW MENU N A A A te 2 6 2 310018 menu Zu Heer a IR Bese na 2 6 2 4 Data Menu a ea ee 2 6
71. a the Ending date may also be given as latest which means the newest data available from AAVSO 3 Press Enter or the Get Curve button at the bottom To print the current light curve press Print The Sky View may also be used to specify an object as follows Page 12 10 Version 3 5 2 Tools 1 Position the cursor near the desired sky location in the Sky View 2 Press and hold down the right mouse button 3 Slide down the popup menu to AAVSO and release 4 The 5 stars in the AAVSO that are nearest to the cursor position are shown in the list in the upper right sorted by ascending order of distance 5 Click on one entry in the list to move it to the Name and Designation fields on the left and proceed as above to display a light curve Or if the date ranges are already set as desired double click the entry in the list and the curve will be fetched immediately The database AAVSO edb is specially tailored to match the official names of stars maintained in the databases at AAVSO Using this database will facilitate the selection and retrieval of AAVSO light curves Databases can be changed from the Data gt Load Delete menu in the Main window 12 7 SETI home SETI home client directory setiathome setiathome 3 0 Refresh Auto refresh Sky Point Sky Mark Refreshed Wed Nov 29 01 38 50 2000 GMT User name User email Registered Total CPU Work units Last Sent Work unit Recorded Position Receiver Fre
72. ace Telescope Science Institute STScl in the United States or the European Southern Observatory ESO research facility in Germany The image data from either site is identical so choosing which to use depends only on availability and whichever is faster for you The size and position of the image are that of the current Sky View settings but the size limited to 30 arc minutes by agreement with each institution Before attempting a download use the File gt Network setup window off the Main menubar to configure your Internet connection Pressing Get will begin the download A progress meter will display remaining time A Stop window is provided if you care to abandon the effort The header of the http server response message is in the Main File gt Log window check there if an error occurs FITS Header This section consists mainly of a scrolled text area which shows each field in the FITS header If the header contains any of the fields EPOCH JD or DATE OBS then the date of the observation is displayed above the header A button will also come alive which allows setting the main XEphem time and date to this value This is handy when checking for asteroids comets or using the proper motion catalogs with an image In order to be displayed the header in a FITS file must contain at least the mandatory fields SIMPLE BITPIX NAXIS NAXIS1 NAXIS2 and END Only files with BITPIX 16 and NAXIS 2 are supported Both DSS PLATE headers and the tra
73. age scale is known from header fields CDELT1 and CDELT2 The pixel value representative of the noise level base in the area B in the above equation The pixel value of the peak of the Gaussian fit A B in the equation If there is a number in the Reference Mag text field it is simply added to the magnitude reported The idea is to set this to the magnitude of a star known by independent means and use that star as the reference for subsequent comparison Since the reference is now calibrated magnitudes reported will be absolute not just relative Except under special situations the reference star will not be applicable to other images although XEphem does not prevent you from doing this The reference star can be established in a few ways One way is automatic in the sense that if there is no current reference the first star that is measured is also automatically given the role as reference for subsequent comparisons After any star has been measured it can be made the reference by clicking on New Clicking Mark will draw a small circle in the image around the current reference star Another way to set the reference is to use a catalog star This is only possible of course if the header includes WCS coordinates Right click on the catalog star and choose the entry New Photom ref This will perform the Gaussian fit on the pixels at that stars location in the image and assign the Reference Magnitude to the catalog value This sect
74. al changes The idea here is generally to match the time values of each time mark with the precision implied by the format but to allow other options as necessary Number of tick marks This is specified by setting the scale near the bottom of the dialog to the desired number Once the choices are set up as desired Ok will create the trail and the dialog will disappear Apply will create the trail but the dialog will remain up for further use Close just dismisses the dialog without creating a trail Help brings up this message Even with all this flexibility pleasingly annotated trails are not trivial to generate It is hoped that a little experimentation can yield acceptable results in most cases Note that this general trail facility does not provide close coupling with the view being supported For example some views do not support setting a trail for an object which has changed while the Trail Setup is up Also views may vary in their support of having trails defined while they are not visible Each view may establish its own initial default values but changes usually remain in effect for subsequent instances of Trail Setup dialogs from the same view Some views permit more than one Trail Setup to be active at one time In short the operational boundary conditions vary by view Page 15 2 Version 3 5 2 LX200 16 Meade LX200 Support This chapter describes how to operate a Meade LX200 or compatable telescope from XEphem The d
75. ame star from the various catalogs Two stars are considered the same if their positions match within 4 arcseconds and their magnitudes differ by less than 3 The generous magnitude tolerance is because the GSC and the PPM use varying filters When deciding on the final selection for such duplicate entries the highest priority is the local database then the HD or SAO entry then the PPM entry then Hipparcos then Tycho and finally the GSC entry When you have made the desired entries pressing Apply will attempt to check each filename directory and Internet choice as appropriate The cursor will be a Watch while the tests are in progress If something does not seem correct a warning window will appear and the option will be turned back off If everything seems to be operating correctly you are in business The Ok button does the same thing but then also closes the window if they all succeed If at any time during normal operation something goes wrong during the acquisition of any Field Stars or FITS files from any View the responsible option in that view is also turned off automatically Page 13 14 Version 3 5 2 Data All field star sources will silently enforce limits on the total number of stars they yield for any query As of this writing local queries are limited to 15 degrees network queries impose their own limits FITS and DSS images are limited to sizes of 20 arcminutes or smaller Version 3 5 2 Page 13 15 Data Page 13 16 V
76. an Measurements Close Help in the table include Abel1426 fts 530W x 530H Max 47620 at 33 99 Min 35559 Mean 36792 1 Median 36498 StDev 1179 2 J Brightness and Contrast Help Cross section Slice Help Magnifying Glass This section gives control over and Help O Region of Interest shows information about the pixels Help 1 2D Gaussian Measurements in the magnifying glass Close Help Click and hold the left mouse button as you roam over the image and you will see an expanded view of the pixels The Size and Magnifying power of the glass can be set as desired using the two rows of toggle buttons Note the numbers on these buttons are in units of screen pixels not image pixels So for example if you zoom in on an area the magnifying glass will expand it correspondingly further While roaming you might want to turn on the Jump to Max Se button on the right hand toolbar lt is the one with the bright Em dot in the center to which a meandering arrow finally points When this button is on XEphem will begin at the pixel under the real cursor and walk the gradient to the brightest connected pixel All processing proceeds as though this brightest pixel is where the cursor really pointed Statistics about the image pixels under the glass are shown in the table All values are in pixels all locations are in image coordinates Fractional image coordinates occur because the image is resized to fit the window whic
77. an X Windows server on your system there is a small chance of a conflict To reduce this further XEphem and MI X are set to use display 1 This can be changed to display N for XEphem by editing the Target Property of the desktop and Start shortcuts to display N and for MI X by changing the Network Port number preference to 6000 W If all this means nothing to you consider yourself lucky The installation will insure you select a disk with the required amount of free space After installing the MI X server you will get an instance of Explorer showing the files it installed which you can just dismiss The final step is to reboot When your computer comes back up you will find a new shortcut for XEphem on your desktop and in the Start menu under Programs gt Clear Sky Institute Inc 1 3 1 Starting XEphem the First Time Start XEphem by double clicking on the XEphem desktop shortcut You will see an Authorization dialog Ignore what it says about buying a license from Microimages That was already included in your XEphem purchase For now you can just click on Ignore However within 15 days you must obtain a valid authorization code from us There is no charge for this code but you do have to send us an email to get it To obtain your code send the machine ID exactly as it appears as the only thing in the body of an email and send to xewinregister clearskyinstitute com Page 1 6 Version 3 5 2 Introduction The Subject of the email will
78. and show it in the color patch You can select history entries with the mouse or by browsing with the Up and Down keyboard arrow keys When a color context is changed it also changes the corresponding resource In the Preferences gt Save window you will notice that the resource becomes marked as Modified after you do a Refresh This allows you Save the new color choice permanently If you do not Save it the change only effects XEphem until you exit 2 6 Sites dialog This window allows you to load Scrolled list of all sites Abilene Texas Se Adelaide SA Australia search and select one of a Akron Ohio l Albany New York collection of predefined sites augura N e Search for next site A A a US containing this string Alerto Penneyivane The scrolled list at the top lists ne fee the complete set of currently Set this site in the eee ee defined sites Clicking on one Main menu Ay N i i i sear Eg will copy it to the Set text field Saitis SE en as Double clicking on one will also r File fusr local telescope xephem auxi1 xephen install it to the Main window as Steet EEE will clicking on Set or typing rowse fora ____ Enter over the select text field sites file 0s Hesg Version 3 5 2 Page 2 13 Main Window To search for a particular site either scroll through the list or enter any part of the site designation in the Search text field Clicking on Search or typing Enter in the search text field will
79. as candidate values for the user defined objects and all of them can be displayed in the sky map subject to type and magnitude filters The format of the database file is described in the Help for the DB window 1 2 UNIX Installation To install from the CDROM you just basically mount it and run the install script You must be root to perform the installation because several files are placed in system directories Also check the README for any last minute instructions Accessing the CDROM drive is the first step For example on Red Hat Linux the following is typical su Password mount mnt cdrom mnt cdrom install Some systems use just cdrom Once you can access the CDROM run the install script mnt cdrom install In rare cases your system may have been configured to prevent execution of programs directly from the CDROM If this happens the above will complain immediately and exit The solution is to copy the script to some place on the hard drive and run it from there For example cp mnt cdrom install tmp chmod u x tmp install tmp install mnt cdrom Note that in this scenario you should run install with one argument the full path to the CDROM Version 3 5 2 Page 1 3 Introduction You will now be asked a short series of questions As appropriate each question may be followed by the possible responses in parentheses and a default in square brackets that is used if you just type Enter For exa
80. as the new reference for photometric comparisons and the magnitude of the object from the database is set as the reference for subsequent use Telescope GoTo This will cause the coordinates of the cursor to be sent to a fifo which is typically connected to a telescope control process The command is not issued if the coordinates are below the horizon This button is only present if the connected process is running See Help gt on Telescope for more information AAVSO This will search the AAVSO database for the nearest objects and place them in the list of the AAVSO tool See the Help for the AAVSO Tool for more information on downloading the light curve 12 6 Version 3 5 2 Page 10 5 Sky View Assign gt to ObjX to ObjY to ObjZ This cascade allows you to assign the given object to become ObjX Y or Z as desired see 813 3 This will also cause all other views which are currently making use of this object to be updated and the object will be added to and selected by the Data table Also since this makes the object one of the User Defined objects it will now appear directly in the Sky View gt Locate pulldown menu Show in Data Table This option is only offered when the object chosen under the cursor is a planet the Sun or the Moon Selecting this option forces the object to be enabled in the Data Table Persistent Label gt on Left on Right This cascade will toggle whether a label is drawn on the left or right
81. ata is exactly the same as for any XEphem database file Due to the way the fifo data is read and processed it is important that each line be terminated with a newline incomplete last lines can result in loss of information No Dups If this toggle is on then when a new database file is loaded objects from other catalogs whose name already exists in memory will be silently skipped This option does not check for duplicates among the user defined objects ObjX Y Z nor entries within the new file itself Load Obj when 1 If this toggle is on then when a new database file is loaded and it defines exactly one object it will also be assigned to one of the user defined objects ObjX Y or Z The one affected is the first which is either undefined whose name matches the new object or ObjZ This feature is also available for files loaded when XEphem first starts Close Closes the Data Base window Page 13 2 Version 3 5 2 Data 13 1 2 edb File format Follows is the description of the format of an XEphem database file The file name extension is edb General Information Each object occupies one line in the file Lines are separated into Fields using commas Some fields are further subdivided into Subfields with vertical bars Lines beginning with anything other than a z A Z or 0 9 are ignored and may be used for comments The order of objects in a file does not matter Where they appear all date fields may be in either of t
82. atalogs usno If USNO was not installed initialled just copy it here later when you decided you want to use it fifos is used for communication between XEphem and the LX200 driver fits can be used to store image files in FITS format 1 3 3 Multiple Users The shortcut installed on the Windows desktop and in the Start menu under Clear Sky Institute define the paths to the Nutc and XEphem directories for the current user If your installation is to support multiple user accounts they should all point to the same Nutc directory but to individual XEphem directories To see how these are set up right click on the desktop shortcut for XEphem and select the Properties menu entry The two fields of interest are Target and Start in Target specifies the full path to the xephem exe executable followed by an argument which specifies the full path to the private directory to be used by one user It is this second argument that should be made unique for each user For example c program files clear sky institute inc nutc bin xephem exe env HOME c program files clear sky institute inc Start in specifies the full path to the shared directory which can be used by all users XEphem does not change the files in or below this directory For example Page 1 8 Version 3 5 2 Introduction c program files clear sky institute inc nutc The icon for XEphem is c program files clear sky institute inc nutc bin xephem ico 1 3 4 File naming File
83. bd pl in the text field provided Internet to ESO This choice accesses the GSC catalog service maintained by the European Southern Observatory This choice emulates a web browser query and uses the Proxy or SOCKS facilities described below which should make it accessible to user behind firewalls The CDROM or the cache options may not be used at the same time as the network options Note that the ESO GSC server apparently arbitrarily and certainly silently restricts the total number of stars it will return so larger and or deeper fields may not contain all stars You may also access this service directly from your Web browser at http archive eso org cgi bin gsc USNO A or SA catalogs This choice of field stars supports the SA or even the A series of astrometric catalogs produced in recent years by the US Naval Observatory The SA2 0 for example includes some 54 million stars spatially sampled so there is about 1 300 stars per square degree of sky Note that such a uniform distribution does not look much like the real sky but it is great for its intended use as an astrometric mesh for comet hunters or such Root directory To order these catalogs see http psyche usno navy mil pmm If you have such a catalog simply enter the name of its base directory and toggle this switch on The default assumes a symbolic link catalogs usno off the shared directory The suggested citation for SA1 0 follows Monet D Bird
84. be connected to a telescope control process This mechanism is the same as that provided by the Telescope facility within the Sky view Please refer to its help for more details in 10 6 Movie Demo This option will set up the time step controls in the Main window for a 15 minute step size and start a loop which dramatically displays the motions of the moons as they orbit Saturn This selection automatically disables the View gt Sky Background selection to insure reasonable speed Push the button again to stop the movie Close This removes the Saturn display and the additional information window if present from the screen Page 8 2 Version 3 5 2 8 3 View menu Top view Saturn View Selects whether to also display another window looking down on the Saturnian system from above the celestial N pole This window will tend to remain aligned above the main view when either is resized Moons are displayed only if they are in sun light Sky background Selects whether to also show objects within the current field of view that are in the XEphem database memory or available from the Field Star facility The size of the object is determined by the limiting magnitude as specified by the scale at the right Objects are drawn using the same symbols as used by the Sky view While this option is on XEphem will continue to retrieve field stars as required Bright moons If this option is in effect then the diameter of all moons w
85. be ignored You will receive a reply back to the address from which your ID was sent containing an Authorization Code before your gratis period expires The machine ID depends on your hardware and the code will only work on that one computer system Once you enter a valid code you will no longer see this dialog After clicking through the Authorization window you will see a large black window a small Workspace Overview window explained shortly then after a short while XEphem s Main window If you took more than a few moments to ponder the Authorization window then XEphem probably gave up waiting and you will just have a black window forever If so just close the workspace click on the x in the upper right like you would close any Windows app and start XEphem again this time clicking Ignore right way See the rest of this manual for using XEphem The Overview window allows you to control the MI X workspace that is in effect larger than your screen and completely dedicated to XEphem s windows You will find this very handy because XEphem has many windows which you may want open at the same time and this gives a handy way to manage them all The Overview window represents the entire workspace in miniature The red box represents the portion of the workspace currently visible You can move this visible space around by clicking inside the red box and dragging it around or by using the scroll bars on the right and bottom edges of the screen Al
86. been divided into two classes Most resources are deemed suitably interesting that they can be automatically Saved whenever they change These are called Major resources Other resources are considered Minor in nature meaning the user is likely to change them frequently while operating the program and saving them at any one particular setting is not especially compelling These are basically window size and position scale settings which only effect viewing angle and all of the Sky View Filter and Option settings This distinction is of course rather arbitrary however so please take care when changing and saving resources so just the ones you want are saved In the expanded view each resource and its value are shown exactly as it would appear in the disk file if Saved Those resources which differ from the last time they were Saved or since XEphem was started if no Save has yet occurred are marked with a bullet A toggle next to each resource allows individual selection over whether the resource will be written to disk on the next Save After each Refresh Major resources which are found to be out of date are marked with a bold bullet and automatically selected to be Saved if the Autoselect option on top is active Minor Version 3 5 2 Page 2 9 Main Window resources are marked with a hollow bullet mark and are never selected for Saving by default If at least one Major resource is out of date in a category a bold bullet is placed next to the ca
87. by one or more blanks or tabs All lines not having exactly three floating point values are ignored and may be used for comments etc 2 2 View menu The View pulldown brings up any of the several XEphem specialized displays Each has its own Help so please refer to them for additional information on a particular function 2 3 Tools menu The Tools pulldown brings up windows allowing full control of the following functions plotting data listing data equation solving finding close pairs seeing the night at a glance retrieving AAVSO light curves monitoring your local SETI home client typing in and converting between coordinate systems Each tool has its own Help so please refer to them for complete information on a particular tool 2 4 Data menu The Data pulldown brings up windows which pertain to managing the objects in memory Load Delete adds and deletes catalogs of objects to and from memory The window also displays overall statistics of the number of each type of object in memory Download Internet files provides a convenient means to update XEphem databases from the Net The window comes preconfigured to get timely asteroid comet and Earth satellite catalogs Search memory ObjX Y Z selects any given object in memory and views or modifies all of its defining parameters Also can be used to center the Sky View over any object and to define the user defined objects ObjX Y and Z Page 2
88. cal Society of the Pacific Mount a CDROM somewhere onto your filesystem type the name of the mount directory in the text field provided then turn this option on and press Apply Note that XEphem assumes your CDROM driver removes the trailing 1 from all filenames Local Cache Directory This choice enables reading GSC field stars from your local disk If this option is on along with the CDROM option then as requests are satisfied from the CDROM a compact form of the same data will be written to files below the directory named in this option Then the next time the same field stars are needed and this option is on they will be obtained from the local disk files rather than the CDROM In fact the CDROM is not needed or used if the local disk contains all the stars for any given access The entire 2 CDROM set loads onto disk in this format in some 180 MB The default path of the directory which holds the disk version is catalogs gsc off the shared directory Note There is also a utility in the tools gsc directory gscload with which you may preload an entire ASP CDROM segment at once if desired These files are already included in the commercial version of XEphem Internet to xephemdbd This choice is to use the Internet to access an XEphem GSC server See the XEphem home page for the current list of GSC server hosts Page 13 12 Version 3 5 2 Data To use this source select this option and type the URL to the remote xephemd
89. cifies they be treated as signed with values from 32768 through 32767 2 XEphem image coordinates are one less than the FITS standard FITS defines the center of the first pixel in the file to be at 1 1 while XEphem defines it to be at 0 0 Page 10 20 Version 3 5 2 Sky View 10 4 2 1 Brightness and Contrast This section controls the mapping between image Hep otis Mage at sels pixel lors iy section ee a a pixels and screen colors It does not modify image Median 36498 StDev 1179 2 pixels In any way Black stars Help Brightness and Contrast Reverse Sharper Brighter This section may be opened using the button a Shortcuts Nominal Duller Darker in the left Sky View toolbar that looks like a Narrow Wide Full circle filled with black on the right half Numeric black z z o gt 85612 89150 Hi and white pixels The top nine buttons offer shortcuts to set or adjust the image appearance according to predefined algorithms Gamma scale Histogram Brightness Help Cross section Slice assignment e Reverse toggles between assigning brightness in Sie O apagas direct or inverse proportion to image pixel values Help Region of Interest Help 2D Gaussian Measurements Narrow Wide and Full correspond to high medium Close Help and low contrast settings These are implemented using increasingly broader assignments of brightness about the mean pixel value in the image Narrow assigns full
90. ct on existing eyepieces 10 3 8 Coordinates This is a handy means to bring up the Main Tools gt Coordinate converter Please see its own help for full details 12 8 10 3 9 Tracking Please see the description for this button in the discussion for the Sky View Control menu 10 3 10 3 10 Close This causes the Sky view and all supporting dialogs to go away Version 3 5 2 Page 10 17 Sky View 10 4 Images Menu This menu controls Sky View s image display capabilities 10 4 1 Load and Save Time image was taken a Se Get Digitized Sky Survey image a From STScI ESO Set XEphem time Which institution V Survey DSS 1 DSS 2 Ss 2B BER image time Which survey FITS Header 1957 12 20 05 41 43 Set time SIMPLE T FITS hea Scroll FITS BITPIX NAXIS NAXIS1 16 No Bits header fields 2 No dimen 530 Length X MR youn OSI Adlust proportion of ir ate H Monitor file for ORIGIN CASB STSCI Oria o window used for header name of FITS file _ PLTLABEL E1618 Nfoservat ps II E a E to load Name of file TENE DA La Save image to disk now to monitor 1 gt home ecdowney xephem watch txt 4 Build a reasonable name eer Save as Save now Auto name i home ecdowney xephem Abel 1426 fts Sl N File to be written if saved Open Look in Private Shared SILO Handy jumps Scrolled list of fhome ecdowney xephem Ft Mes to bean directories at this level
91. ction displays seti home client progress and plots position being processed on Sky View map provides a handy spreadsheet for converting among equatorial ecliptic horizontal and galactic coordinates includes a compiler for entering and solving user written functions using any data fields serves as the control point for GOTO telescopes in real time such as Meade LX200 displays FITS files and DSS images overlaid with properly registered database symbols and other graphical information performs automatic star pattern matching to solve for accurate World Coordinate System on any image performs 1 click 2D Gaussian relative and absolute photometry lets you define and save any number of Eyepieces to use in sky maps displays your own local horizon profile can store sets of Sky View options for easy playback later uses high quality Postscript for all printing XEphem can compute information on demand or time can be set to increment automatically In this way a series of computations and movies can be generated Plot and listing files of selected field values may be generated as the program runs The plot files are full precision floating point values in ASCII intended for export to other plotting programs or XEphem includes its own quick look plotting facilities The listing files are tables formatted for more general human reading Quantitative information available about each object includes RA and Dec local azimuth and alt
92. currently in the field The object is marked even if the object does not match the Sky View filter or is outside the magnitude range The only time the object will not be marked is if the display mode is set to Alt Az mode and the current working object is below the horizon Sky Mark will draw a cross hair on the Sky View window at the location of the current working object but only if it is already within the Sky View field of view The Sky View window is never re aimed with this command Version 3 5 2 Page 13 7 Data Set Tel will cause the coordinates of the current object to be sent to the xephem_loc_fifo fifo which is typically connected to a telescope control process The command is not issued if the object is currently below the horizon See the discussion at Sky_View gt Help gt on Telescope for more information 10 6 13 3 1 Fixed objects Fixed objects are characterized by five parameters RA Dec magnitude the reference epoch for the coordinates and angular size in arc seconds optional Note In order to conserve memory usage XEphem stores the astrometric RA and Dec for a fixed object only once with each object These values are always precessed in place to the current display equinox Thus you will find that the RA and Dec displayed for a given object may change ifthe equinox is changed on the main menu and the object information is redisplayed here on the ObjX Y menu 13 3 2 Elliptical objects E
93. d displayed The button is labeled Change Trail if the selected object already has a defined trail Only one trail per object is supported 10 3 Control menu Page 10 6 Version 3 5 2 Sky View Options This brings up a window with several choices effecting the way the scene is drawn It has its own Help Filter This allows selecting the types and magnitude ranges of objects to display This window has its own Help Print This allows printing the current Sky view or saving it to a file If an image is currently being displayed it will also be part of the print image It has its own Help List This brings up a window that allows saving the objects currently displayed in the Sky View to a file It has its own Help Horizon This activates the Horizon setup window To display the Horizon profile turn on the toggle under Option For more information about this facility see the Help from the Horizon window 10 3 5 Field Stars This activates the Field Star setup window To display Field Stars turn on the toggle under Options For more information about this facility see the Help from the Field Star window itself 13 4 Eyepieces This brings up a window which allows you to specify the shape size and style of the next eyepiece to be created It has its own help Whether eyepieces are shown at all is controlled by the Control gt Options gt Eyepieces option 10 3 7 Coordinates This brin
94. d controlled by the XEphem resource DateFormat selects which form is currently being used As with time components omitted when entering a new date retain the current value For example if the current date is 10 20 1988 and you type 20 30 the new date will become 20 30 1988 If you then type 2000 the new date will become 20 30 2000 Note you must type the full year since the program is accurate over several centuries either side of 1900 If you change the date the time i e partial day will not change Negative years indicate BC dates For example Jan 1 1 BC is given as 1 1 1 There is no year 0 Two other ways to set the date are supported for compatibility with some published comet ephemerides You may enter the day portion as a floating point number When you set the day this way the time will also change to correspond to the fractional portion of the day For example noon on Jan 2 1995 may be entered as 1 2 5 1995 You may also enter a date as a decimal year as in 1990 12345 Also when the date format preference is set to M D Y or D M Y the decimal point may be omitted if the value is nota reasonable month or date value respectively Decimal years are useful in interpreting plot files that include a date field since date fields are stored in plot files as decimal years Any input that includes exactly one decimal point is assumed to be a decimal year Other parameters such as declination azimuth altitude longitude lati
95. data every other day for 182 steps i e span about one year Main gt N Steps gt 182 Main gt Step gt enter 2d then select Ok or type Enter Give the plot a title in the text field provided Version 3 5 2 Page 2 21 Main Window Type Local Sun Dawn Rise Set Dusk time for 2001 Define a file to contain the plot values Plot gt enter a file name in the text field such as sun2001 plt Start capturing XEphem plot data to the plot file Plot gt Create plot file Let XEphem run Main gt Update Note that as it runs XEphem does not update many values and they are made to look unusual This is for speed It only does this if Main gt Pause is set to 0 If Pause is anything greater than 0 all values are drawn In any case internal values are always updated it s just the display that is eliminated for a little more efficiency Also things will go fastest if the Data Table is only showing what is necessary such as turning off all but the Sun row in this case When it stops display the year of plot data Plot gt Show plot file Note how the Plot gt Create plot file option is automatically disabled Also note the spring and fall discontinuities in the plot if you observe Daylight Savings time in your time zone Change the X axis label to be a little easier to relate to Plot gt View gt Show X Axis as Dates Here is an example for Chicago Control View Chicago 2001 Sun Dawn Rise Set Dusk time 2 4 6
96. ditional World Coordinate System fields CTYPE CROTA CRPIX CDELT and CRVAL 1 and 2 are supported BSCALE and BZERO are not support at this time Caveats XEphem treats the 16 bit pixels as unsigned values from 0 through 65535 unlike the standard which specifies they be treated as signed with values from 32768 through 32767 XEphem assigns the coordinate 0 0 to be the center of the first pixel in the file unlike the standard which specifies this position be at coordinate 1 1 File watch This feature allows XEphem to automatically display FITS files that were created by another program All that is required is to arrange for that program to write the path to the new file to the file named in the text field provided here When Watch is turned on XEphem will try to open this file on a regular basis and read the first line If successful the file is displayed and as a simple handshake to the originating program XEphem removes this communication file With this feature and the popularity of various networked file systems NFS Samba etc it is quite reasonable to display images with XEphem that were captured on an entirely different computer Or even on the same computer to use camera control software entirely unrelated to XEphem A further note to implementors XEphem also supports this file being a fifo In this case XEphem will open the fifo and block trying to read a path name up to the first newline There is no handshake in thi
97. ds The model may be expressed as m g 5 log10 D 2 5 k log10 r where m resulting visual magnitude g absolute visual magnitude D comet earth distance in AU k luminosity index and r comet sun distance Note that this model does not take into account the phase angle of sunlight 13 3 5 Earth satellites Objects in Earth orbit are characterized by 9 parameters the parameters that define a geocentric elliptical orbit These orbital parameters are in order Epoch of the measured values inclination degrees RA of ascending node degrees eccentricity must be lt 1 argument of perigee degrees mean anomaly degrees mean motion revolutions day orbit decay rate revolutions day 2 integral reference orbit number at Epoch XEphem treats all earth satellites as if they had a visual magnitude of 2 0 13 4 Field Stars Hubble Guide Star Catalog GSC ASP CDROM Directory mnt cdrom Local Cache Directory usr local telescope xephem catalogs gsc Internet to xephemdbd clearskyinstitute com cgi bin xephemdbd xephemdbd p1 Internet to ESO USNO A or SA catalogs Root directory usr local telescope xephem catalogs usno Proper Motion catalogs PPM catalog usr local telescope xephem catalogs ppm xe2 Hipparcos Tycho2 usr local telescope xephem catalogs hiptyc2 xe2 Skip likely duplicates Ok Apply Close Help Version 3 5 2 Page 13 11 Data This window allows you to control which field star so
98. e and display high quality photometric and astrometric information about the star nearest the cursor based on 2D Gaussian fitting All of these are describe more fully in the Help gt on Images section Middle button While the middle button is depressed the cursor is changed to a fleur pattern Moving the mouse left and right is like moving the scale at the bottom moving it up and down is like moving the scale at the right This provides a simple method to pan the display This feature is not yet available while displaying an image If the Live dragging option is turned on see Control gt Options the panning occurs immediately If this is painfully slow on your system then turn this off so the screen is only redrawn one time when the button is released Right button If the right button is clicked over the Sky View then a popup menu will appear If the button is clicked and released the menu will stay up and can be used like any other menu Or the button may be pressed and held while you slide the cursor to the desired button and let go Try both and use whichever procedure you prefer The popup contains information and controls germane to the exact position of the cursor when the button was clicked The entries in the popup menu vary depending on whether the cursor was near an object or over empty sky Page 10 4 Version 3 5 2 Sky View If the cursor is near a object data is shown which are exactly the same as that which
99. e Data table Since this makes the object one of the User Defined objects it will now appear directly in the Solar System gt Objects pulldown menu Show in Data Table This option is only offered when the object chosen under the cursor is a planet the Sun or the Earth Selecting this option forces the object to be enabled in the Data Table 3 Both the Sun and the Earth actually enable the Sun in the Data Table Version 3 5 2 Page 11 1 Solar System View 11 2 Control menu Print This selection allows printing the current Solar System view or saving it to a file Create Trails This button will bring up a window to set up making a trail 15 for each planet and user defined object as they travel from their current positions Each trail time is drawn connected together with a solid line with each point indicated with a small dot The time stamps shown with the trails if any are always in UTC For the trail to be visible the Trails option must be activated Only one set of trails is supported at a time Creating new trails will delete the old ones The trails will also be discarded if a user defined object is changed or an Update occurs from the Main window Only the basic planets and user defined objects if defined are trailed The other solar system objects if any are always shown in their current positions See the Help from the trail setup window itself for more details on how it operates Movie Demo This pus
100. e details on how it operates Center As long as this toggle is On the given object will remain centered in the display to the extent possible Only one object may be in control at a time When all of these toggles are Off the Earth view will remain fixed unless changed manually via the Scales on the edges setting from Main or using the Mouse controls This toggle is automatically turned off if any of these manual methods are used Popup obj This toggle selects the object to which the Button 3 popup s Alt Az info refers as seen from the current Main menu position SubLat SubLong The latitude and longitude of the ray connecting the object with the center of the Earth These values are shown for all types of objects The following data are only available for Earth satellites Alt Height above sea level Range Distance from the Main location to the given satellite Range Rate The rate of change of the Range distance with positive moving towards the Main location Sun lit 1 if the given satellite is currently in sun light else 0 if it is eclipsed Page 5 4 Version 3 5 2 Earth View Age The difference between the current XEphem Main time and the epoch of the TLE orbital elements in days The larger this value the more the satellite location will be in error Errors depend on drag maneuvers and initial state vector quality Each of these values may be used for plotting solving and listing in the usual way
101. e of excellent quality but Lowell s list is some 20 longer When the Get button is clicked XEphem downloads the appropriate file uncompresses it reformats it to edb format and splits the results into two files for convenience One file will contain all asteroids which can ever become brighter than magnitude 13 and the other with a _dim suffix contains all the rest The search pattern facility does not apply to these files All files are created in the user s Private XEphem directory Special thanks to these organizations for their service 13 3 Search Obj X Y Z Undefined lt gt Hyperbolic 0bjx Achernar This window allows you to select inspect and modify Fixed Parabolic lt 0b3Y Alen any object currently in memory It also allows you to AA E AE TE control the user defined objects ObjX ObjY and Name 40 10 Altair ObjZ Ep of Perigee 2001 77 and 2 sri in E XEphem supports three user defined objects Eccentricty 0 602861 And 5 denoted ObjX Y and Z These may be fixed objects Arg of Perigee 189 625 And 6 objects in elliptical hyperbolic or parabolic SB KANDMA hy 199 344 m heliocentric orbits or objects in geocentric elliptical pe ee 2 05862 and 3 orbits The ObjX Y window allows you to define these Orbit decay 0 And 10 H Orbit reference 10984 and 11 objects Drag coefficient 1e 04 And 12 And 13 XEphem maintains a working copy of these objects a for use with the ObjX Y Z window that is
102. e points The stars were chosen for their proximity to this grid not for their magnitude Indeed most bright stars are not in this catalog at all but it does contain some stars down to as dim as 20th magnitude The result is that the catalog is very useful if you want to perform careful positional measurements on images but is otherwise not interesting for general use because it does not ook at all like the real sky That s all the questions Now the real work begins As the script proceeds it creates a list of all files created on your system during installation in the file tmp xXEphem 3 4 1log The basic activities are as follows create a default resource file in Application Defaults create an initial empty Private directory create a file xephemrc in your home directory pointing to your Private directory copy the appropriate binaries to the Executables directory copy the man page to the Manual page directory copy all the files needed to the Base Installation directory This will take most of the install time and a running progress percentage will help you judge when it will finish if the USNO catalog was chosen a background process is now started to decompress it create the fifos needed for telescope control If all goes well when the install script completes you may run XEphem 1 2 1 Launching XEphem XEphem supports the following command line arguments env N V set alternate env Name Value help print this
103. e sure the option to Install fonts is checked Note the installation directory For the purposes of this discussion we assume you install at c gs 3 Bring up any XEphem Print dialog For example from the Main window click Views gt Sky View then click Control gt Print Check the Print command and make sure it appears exactly as follows case is significant c gs gs7 00 bin gswin32c exe sDEVICE mswinpr2 If the version has changed from 7 00 or if you installed ghostscript some place other than c gs then change this part of the command accordingly If the Print Command is already correct you are finished If you had to edit it there is one more step 4 Back in the XEphem Main window click Preferences gt Save and click on the Save button at the bottom This will make the change to the Print Command permanent for this user Now when you Print from XEphem ghostscript creates a normal Windows print job which you manage like any other We find this print window is sometimes buried beneath the XEphem workspace so you may have to find it on the Windows Taskbar and bring it to the front before you can use it Version 3 5 2 Page 1 9 Introduction 1 3 6 Uninstallation To completely remove XEphem and all its supporting components click on Start gt Settings gt Control Panel Then double click on and open Add Remove Programs Remove the following programs in order MKS Platform components 7 x Microimages X Server XEphem
104. e the limiting magnitude so we can see fainter things Sky View gt Control gt Options gt Coord RA Dec Sky View gt FOV gt slide to 2 0 Sky View gt Control gt Filter Sol Sys Lim Mag gt slide to 14 Stars Lim Mag gt slide to 14 Deep Sky Sys Lim Mag gt slide to 14 Ok You ll probably want to use the Topocentric preference from the Main window Main gt Preferences gt Equatorial gt Topocentric Open the Close objects window build a list of all moving objects within say 1 degree of each other Main gt Tools gt Find close pairs Close gt Max sep gt enter 1 0 Close gt Mag limit gt enter say 13 Close gt Options gt Omit fixed pairs if not already on Close gt Control gt Go might take a moment Now scroll through your set and find something that looks good For Version 3 5 2 Page 2 15 Main Window example tonight happened to find asteroid 702 Alauda passing within 16 arc minutes of the bright open cluster NGC 6416 Double click on the row and the Sky View will swing around and show it to you You might want to tweak up the field of view a bit If you ve chosen an asteroid let s plot its motion over several hours Put the mouse near the asteroid click button 3 pull down to Create Trail and let go You ll get a trail setup window Trail gt 1 Hour Trail gt First Mid Last Trail gt Number of intervals enter 24 Trail gt Ok If you get a wild array of lines be sure Sky View gt Con
105. econds 0 11 20 2000 7 56 07 UTC Close Help This button brings up a separate window which contains quantitative information about Mars s moons All values may be used in plotting listing and solving The E and S columns are 1 if the moon is visible from the Earth and Sun respectively The locations of the moons are given in two coordinate systems The first three columns are the displacements of the moons in Mars radii with respect to the celestial plane The next two columns give the RA and Dec location of the moons in the current epoch as specified on the Main window Page 6 6 Version 3 5 2 Jupiter View 7 Jupiter view e South Pole Pole View Sunlight terminator l Orientation ll to Earth Control View Help Earth View 5 Galileo image morphed to Equatorial current Earth view orientation Limiting Moon with magnitude standard tag a Elg Ul i Zoom HA Y Image 1 scale 8 20 2001 16 26 12 CDT This is a view of Jupiter and its Galilean moons at the indicated date and time In addition background sky objects may also be displayed The scale at the left controls relative magnification The scale at the right controls the dimmest magnitude which will be displayed Jupiter is always displayed The values range from 20 at the top and 0 at the bottom Objects dimmer than the value specified are not shown Equatorial directions are indicated at the top and right edges Moons are displayed
106. ed The azimuth ranges from 0 up to 360 degrees Any values outside this range have 360 added or subtracted until they fall in this range The lines need not be sorted by Azimuth although they will be sorted when used thus the horizon map can never cross itself If the file does not include the full range of Azimuths the end points will be connected automatically It is ok to specify just one point at any Azimuth This will result in a flat horizon all the way around at the specified Altitude This is functionally equivalent to using the Fixed Displacement method Values in between those in the file are computed by linearly interpolating the two nearest surrounding points 10 3 6 Field Stars This selection activates the Field Star setup dialog For more information about this facility see the Help for the Field Star dialog itself 13 4 Version 3 5 2 Page 10 15 Sky View 10 3 7 Eyepieces Width and Height Moving einer of next eyepiece DD MM moves both Set next eyepiece size shape and style ul 2 25 Special case to dilaton Next eyepiece make next eyepiece Lock scales together Shape and Size Angle subtended by a Telrad pattern A target on sky Create a Telrad pattern Linear size or AEn style OSolid target on Rectangular Outline focal plane Re Copy sky angle result y Field of View Calculators to eyepiece ml pus Focal th F pisne Size Sky angle Set WorH ocal leng ee mm m
107. ed running and the Marker turned on in the Sky View you should see the telescope target symbol at the same RA and Dec reported by the LX200 hand paddle display The Sky View will automatically reposition itself as necessary in order to keep the marker visible If the cursor is outside the Sky View the coordinates of the marker are shown in the upper corners Version 3 5 2 Page 16 1 LX200 To move the telescope put the cursor over a sky location to which you would like to point the telescope and press the right mouse button A popup will appear Without letting go slide down to Set telescope and release This should send a command to the LX200 to move to that location and commence tracking You can watch it move on the Sky View as the marker is updated That s about all there is to it Just point and go Or if you just want to move your LX200 by hand or with its own control paddle you can just watch where it is pointing on the Sky View If you want to aim the Sky View somewhere other than at the telescope turn off the Marker in the Telescope menu first or else it will keep bouncing back to keep the Marker in the field then turn it back on later when you again want to see where the telescope is pointing In anticipation of not wanting this locking on behavior the Telescope Marker is automatically turned off if you use the Locate menu use the Center or one of the Zoom buttons in the popup menu or use one of the Sky Point controls found elsew
108. electing a goal You may choose from any of three evaluation algorithms as selected by the trio of radio buttons Find extreme will solve for a maxima or minima of the function Find 0 will solve for a time when the function evaluates to zero Binary will keep incrementing time by Step in the Main window until the state of the function changes then do a binary search to find the exact time when the function changes state Binary search interprets a function that evaluates to zero to be in one state and all other values to be the opposite state Generally binary functions are comprised of logical operators at their outermost expression levels Specifying the desired accuracy Searching will automatically stop when the time changes by less than the the accuracy value Note that this method of detecting convergence is not based on the value of the search function itself To change the desired accuracy press the pushbutton showing the current accuracy next to the Accuracy label and enter a new value in the window Enabling the solver Once the function is defined and it compiles without errors you may enable searching for a solution by selecting the button at the top labeled Solving is Active Then each time Update is selected on the Main window the solution advances by one time step until either N Steps iterations have occurred or until Step becomes less than Accuracy The initial time and step size are set from the Main window
109. elete window for more information on manipulating this data base 13 1 If there are more than 20 items then a scroll bar may be used to browse through the list The entries are sorted in numeric and alphabetic order ignoring case for easy browsing If one of these objects is picked then it is copied to the current working object You may then edit the values for this working object if desired without effecting the original Below the list of names is a text field with which you may select an object by name Enter a string and type Enter or press the Search pushbutton All objects in memory will be searched for one with a name that contains the string Whitespace and case are ignored To anchor the string to be at the beginning of the objects name precede the string with a caret If a match is found the list is scrolled so the object is at the top and the object is copied to the current working object To select again with the same string type Enter or press the Search pushbutton again XEphem beeps if no matches are found When the current working object is as you want it select Apply to copy it into the real ObjX or ObjY or Z used throughout the other functions of XEphem Ok will do the same thing and also close the window Other controls include Reset load the current working object with a copy of the real ObjX or ObjY or Z Sky Point mark the current working object on the Sky View with a cross hair re aiming if it is not
110. elion i inclination degrees O longitude of ascending node degrees o argument of perihelion degrees e eccentricity q perihelion distance AU D the equinox year i e time of i O o g k two fields which specify the magnitude model s angular size at 1 AU arc seconds optional Page 13 4 Version 3 5 2 Data If the Type is p parabolic heliocentric eccentricity 1 the remaining fields are defined as follows T epoch of perihelion i inclination degrees o argument of perihelion degrees q perihelion distance AU O longitude of ascending node degrees D the equinox year i e time of i O o g k magnitude two fields which specify the model s angular size at 1 AU arc seconds optional If the Type is E Earth satellite the remaining fields are defined as follows Epoch inclination degrees RA of ascending node degrees eccentricity must be lt 1 argument of perigee degrees mean anomaly degrees mean motion revolutions day orbit decay rate revolutions day 2 integral reference orbit number at Epoch drag coefficient 1 earth radii optional The venerable Two Line Element TLE format is also automatically detected and supported For a complete discussion of TLE format see http www celestrak com 13 1 3 Notes XEphem does not use the facility controlled by this window for so called Field Star catalogs See the Help for Data gt Field Stars for more infor
111. ent day with local midnight in the center Across the bottom is a scale marking local dates and time and UTC time at each even hour The current XEphem time is marked with a thin vertical line The background gray shading shows when the Sun is up down and periods of twilight The twilight period matches the Sun Dip setting in the main XEphem window Overlayed on the gray background is one thick horizontal line for each basic object and any of the user objects Objx Y Z that are defined The lines show when the object is above the horizon as defined in the Data View gt Control gt Setup horizon parameter Clicking with the right mouse button near an object s line will pop up its rise transit and set information This is with respect to the day in which the moment occurs corresponding to the mouse click location A button is also included in the popup to set the main XEphem time to this moment If the mouse is clicked far from any object then just the time is presented The lines and text colors are set based on type of object or can all be set to one color using the Control gt One color toggle The window may be printed using the Control gt Print menu option 14 An interesting exercise is to set up a time loop with a Step size of a few days and watch how the rise and set times of objects and the amount and timing of night time are effected throughout the year Version 3 5 2 Page 12 9 Tools 12 6 AAVSO light curves AAVSO
112. ersion 3 5 2 Print 14 Print Title Color Grayscale Save to file home ecdowney xephem xephem ps Print command pr ok Cancel Help This window lets you print the current view or save it to a file In either case the format used is Postscript If you enter a string in the text field labeled Title the string will be printed centered across the top of the page The top two toggle buttons allow you to choose whether color commands will be included in the Postscript generated If you choose to Save to a file turn on that toggle button and type the desired file name in the text box to the right of the toggle button The file name will be relative to the directory from which XEphem was executed or you may precede the file name with to refer to your home directory If you choose to print directly to the printer turn on that toggle button and type a command which will print a Postscript file on your system The command should expect the name of a file to print as its first and only argument A temporary file will automatically be created for this command and deleted when printing is completed When ready press Ok To avoid printing press Cancel If your current viewing fonts are not available for printing error recovery will depend upon your local print system Version 3 5 2 Page 14 1 Page 14 2 Version 3 5 2 Trails 15 Trails Mars Orientation Interval Label Up 5 Minutes Every 1 Down 1 Hour Every 2 Lef
113. ese are generally good to 1 2 arcsecond accuracy In my test against JPL DE405 would say this is true about 50 of the time with a worst case of about 4 AS Version 3 5 2 Page 18 1 Credits Outside this range Jupiter s moons based on information in Astronomical Formulae for Calculators by Jean Meeus Richmond Va U S A Willmann Bell c 1982 Saturn s moons based on code and ideas supplied by Dan Bruton Texas A amp M astro sfasu edu For all dates ring tilts based on RINGS OF SATURN program by Olson et al Sky amp Telescope May 1995 page 95 C code as converted from BASIC by pmartz dsd es com Paul Martz Thanks to Monty Brandenberg mcbinc world std com for his assistance and solution to the unaligned access messages on Digital UNIX Thanks to Christophe Magneville cnv hep saclay cea fr for finding an array subscript and a numeric overflow problem in libastro Thanks to Jean Etienne LAMIAUD tcc thomson csf com for a fix to prevent gif color tables from hogging more than their share of X colormap entries and many corrections to xephem sit Thanks to Stuart Levy slevy ncsa uiuc edu for his work converting the Tycho ESA mission database adc gsfc nasa gov pub adc archives catalogs 1 1239 into xe format Many formulas and tables are based with permission on material found in Astronomy with your Personal Computer by Dr Peter Duffett Smith Cambridge University Press c 1985 The high precision plane
114. est of XEphem For example its computations use a different model for Earth flattening and for refraction These and other differences can lead to modest inconsistencies 5 1 Mouse functions As long as the cursor is over the Earth the four corners of the View will display the following information about the position beneath the cursor Upper left Latitude Upper right Longitude Lower left Local Mean Time Lower right Local Sidereal Time Middle button If View gt Live dragging is On then while the middle button is depressed and located over the Earth map the cursor is changed to a fleur pattern Moving the mouse left and right is like moving the scale at the bottom moving it up and down is like moving scale at the right This provides a simple method to pan the display Right button If the right mouse button is depressed while over the Earth apopup menu appears with information related to the location under the cursor as follows If the location is near a Site information is presented with respect to the exact location of that site otherwise it is with respect to the latitude and longitude of the location under the cursor If the location is near the current or a trailed location of one of the displayed objects information is presented with respect to the location under the cursor and for that object at the time of the trail mark In either case there will also be a button labeled Point that if activated will center
115. exists The preferred width to height ratio for the cylindrical projection is 3 14 1 This ratio is enforced each time this projection is selected by changing the width and maintaining the current window height subject to remaining fully on screen Similarly the spherical projection resizes to become a square by setting the width equal to the height The weather map forces itself to become 640x480 pixels After any projection is selected the window size may be directly manipulated manually from then on as desired Reload map This button is only present when the Weather map projection is enabled Pressing it will cause a fresh weather map to be retrieved Grid This toggles showing grids lines every 15 degrees in latitude and longitude Version 3 5 2 Page 5 5 Earth View Sites This toggles whether a tiny square will be drawn at each location found in the currently loaded Sites file Sunlight This toggles whether the portion of the Earth s surface currently in sun light is highlighted in some fashion When using the Weather map projection the map is darkened where the Sun is currently down and only cloud cover and continent outlines are shown Live dragging This toggles whether the display graphics are updated immediately as the sliders are moved or whether graphics are only drawn after the sliders are released Also if this option is on moving the mouse while holding down the middle button will cause the display to
116. f the cursor are displayed in the upper corners whenever the cursor is over the Sky even when no buttons are pressed These data include Upper left corner RA Dec and Hour angle equatorial coordinates the great circle distance between the current position and the point at which the left button was last depressed constellation name raw image pixel coordinates if displaying FITS image N B FITS coords are XEphem 1 Upper right corner Alt Az and Zenith distance horizon coordinates the volume and page number in the Uranometria Uranometria 2000 and Millennium star catalogs NOTE 1 The coordinates are derived directly from the screen location and know nothing of the displayed objects Thus they neglect parallax i e assume everything is at infinity NOTE 2 If the Telescope Marker is active and a telescope control process is reporting telescope position information then when the cursor is outside the Sky View the data in the corners refer to Version 3 5 2 Page 10 3 Sky View the telescope marker position not the cursor position This information is not displayed if any keyboard keys or mouse buttons are pressed Left button If the Roaming report toolbar button is On and the left mouse button is pressed then the information in the upper left and right corners change into delta information that is the changes in the various coordinates with respect to the position where the left button was last pressed If t
117. following notice Copyright C 1989 1990 1993 1994 Kirk Lauritz Johnson Permission to use copy modify distribute and sell this software and its documentation for any purpose is hereby granted without fee provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation The author makes no representations about the suitability of this software for any purpose It is provided as is without express or implied warranty THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE DATA OR PROFITS WHETHER IN AN ACTION OF CONTRACT NEGLIGENCE OR OTHER TORTIOUS ACTION ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE The pulsar and Radio databases are based on lists supplied by Robert Payne rpayne nrao edu Errors in converting to XEphem are mine The lunar image is based on one found surfing at ftp seds pl arizona edu pub images planets moon fullmoon gif The calculations for the longitude of the terminator and the solar altitude are based on the program colong bas by David Bruning and Richard Talcott published in _Astronomy_ October 1995 page 76 Thanks to Richard Clark rclark Ipl ar
118. from menus above Colors previewed this session Color history Method RGB HSV Color controls 1 000000 696668 Sample color patch a a Name or Fa Name or spec ZN RRGGBB IRFFFFFF This window lets you inspect and change many of the colors used by XEphem The top four toggle buttons determines what happens when an entry in a color context menu is clicked The effects are as follows Get current When this toggle is active clicking a color context menu button will cause the current color for that context to be displayed in the color patch in the lower right corner of this window Get default When this toggle is active clicking a color context menu button will cause the last saved default color for that context to be displayed in the color patch in the lower right corner of this window Set Page 2 12 Version 3 5 2 Main Window When this toggle is active clicking a color context menu button will cause the color currently being displayed in the color patch of this window to be applied to that context throughout in XEphem Restore default When this toggle is active clicking a color context menu button will cause its last saved color to be reinstated Above the color patch are three sliding scales that allow you to define a color using either Red Green Blue or Hue Saturation Value depending on the toggle Hue is the pure spectral color where 0 is red 33 is green 66 is blue and 100 is back to red Satura
119. g correctly to operate the telescope and is a good troubleshooting step when first making your connections Or for those who are easily entertained it can also be fun to pretend you have a GoTo telescope Running This button turns the driver named in the first line on and off When it is click On it starts the driver perhaps in no hardware mode if that option is selected above Close This closes this window Closing the window has no effect on telescope operation Help Shows this text Contact us at xephem clearskyinstitute com if you would like details on how to write a driver for a different telescope If you have the details on your telescope command protocol the driver will be easy to write Version 3 5 2 Page 10 27 Sky View 10 7 History menu Apply is Down Delete Replace Sph Alt Az 90 00 180 00 180 00 Sky above annotated Apply Up Down Delete Replace Sph Alt Az 90 00 180 00 180 00 Sky above clean Apply Up Down Delete Replace Cy RA Dec 12 00 0 00 180 00 360 Equator Apply Up Down Delete Replace Cyl Alt Az 45 00 90 00 90 00 East horizon Apply Up Down Delete Replace Cy Alt Az 45 00 180 00 90 00 South horizon Apply Up Down Delete Replace Cy Alt Az 45 00 270 00 90 00 Mest horizon Apply Up Bow Delete Replace Cy Alt Az 45 00 0 00 90 00 North horizon Add Save Load Close Help This is the Sky View History control window Most of the Sky View settings may be saved and restored as entrie
120. g the date to July 11 1991 time to 17 00 UTC location to Latitude 19 50 Longitude 155 28 and starting a loop with a Step of 1 00 and Pause 1 Be sure to use the Alt Az display mode to get topocentric positions or set the Main Preferences for Equatorial to Topocentric It is also very handy to set to Track either the Sun or the Moon whichever you wish to be centered during the movie Version 3 5 2 Page 10 9 Sky View Flip Left Right Flip Top Bottom These toggle whether the display is shown with a flip in the left right or the top bottom directions respectively Equatorial plane This toggle selects whether a red 3 6 dashed line is shown along the Earth s equator projected onto the celestial sphere Ecliptic plane This toggle selects whether a red 2 2 dotted line is shown along the ecliptic The ecliptic is the plane of the Earth s orbit or as seen from Earth the path of the Sun and the approximate path of the planets across the sky The anti solar point is marked with a small open circle The edges of umbra penumbra of Earth are marked with open circles If Preferences gt Equatorial is set to Topocentric the umbra penumbra are projected at the current distance of the Moon and corrected for parallax if set to Geocentric they are projected at infinity Galactic plane This toggle selects whether a red 1 4 dotted line is shown along the galactic equator and small labeled s are placed at the North and South galactic
121. ge of the cylinder is it shows the entire universe at once Grid Control This group of controls allows you to specify the details of an overlay coordinate grid Grid itself toggles the grid on or off If Auto is on then the size of the grid steps will be determined automatically and shown in the text fields beneath if it is off then step sizes are determined from the values in the text fields Typing into either field then pressing Enter will also turn off Auto and immediately display the grid with the new step size Alt Az and RA Dec selects in which coordinate system the grid will be drawn Label selects whether the grid will be labeled View Options Just dots This toggle effects how stars are shown When the toggle is pushed in all stars are displayed simply as dots of various sizes When the toggle is released each type of star is displayed with a unique schematic symbol These symbols may be reviewed from the Filter window In either case the diameter of the symbol shown is the larger of the object s actual size at the current window scale if a size is specified in the database entry for the object or a size that is proportional to the difference between the object s magnitude and the current faintest magnitude setting This means that at suitably small fields of view the Sun and Moon are shown to scale This is ideal for watching solar eclipses or occultations For example watch the solar eclipse over Hawaii by settin
122. gle is active clicking a context menu button will cause the name of the last saved default font for that context to be displayed in the pattern field and When this toggle is active clicking a context menu button will cause the font named in the pattern field of this window to be applied to that context throughout Get default history list Set XEphem Version 3 5 2 Page 2 11 Main Window Restore default When this toggle is active clicking a context menu button will cause its last saved font value to be reinstated through XEphem Fonts that have been changed from their default values are tagged in the Preferences gt Save window after you do a Refresh This allows you to Save the new font choice permanently If you do not Save it the change only effects XEphem until you exit There are a few situations scattered around within XEphem for which changing fonts at runtime from this window does not work perfectly For example changing to a smaller font does not shrink some windows as much as you might expect Such anomalies are known challenges and do not indicate serious problems After Saving the fonts and restarting XEphem all will work again as expected 2 5 3 Save Colors Action to perform when Control Text Backgrounds Sky Earth Objects Help a selection is made from sit rs Whether a pulldown menu SE ESCO hens Red Green Blue Get current Set or Hue Saturation Value Get default Restore default Then choose target
123. gs up a simple dialog which allows you to type in or copy paste and convert among several common coordinate systems used in astronomy A position defined in any of the coordinate systems can also be mark on the Sky View which will be repositioned automatically if the position is not in the current field of view Tracking Tracking here refers to object tracking and means that the pointing direction of the display will automatically be changed each time an Update occurs from the Main window such that the tracked object will remain centered on the display The object to be tracked is selected by using the Track option in its popup menu as described earlier When this toggle button is sensitive and pushed in it means that tracking is active for one object The tracked object will be marked with an X on the display after each Update If this toggle button is selected while it is sensitive it turns tracking off This is a convenient Version 3 5 2 Page 10 7 Sky View alternate method to turn off object tracking without having to find the exact object being tracked and use its popup Track control When this toggle button is insensitive and popped out it means that object tracking is not active it does nothing when selected while insensitive Close This causes the Sky view and all supporting windows to go away 10 3 1 Options This is a description of the controls in the Sky Options window Note that some of these options
124. h button will set the Main window Step to 5 days and start looping with a very large number of steps Press the button again or use Stop control in the Main window to stop the movie Live Dragging This toggle button selects whether the graphics are redrawn in real time as the various scale controls are being slid or whether the graphics are not redrawn until the mouse is released The decision depends on the speed of the computer display and data bandwidth If the system is fast enough turning this on can produce dramatic depth queues for complex solar system views also try it in Stereo Stereo pair This toggle button is used to bring up another image of the solar system from a slightly displaced vantage point Adjusting your gaze to fuse the two images together will reveal a 3D image This effect is most pronounced if fairly lengthy trails are created and legs are enabled This effect was designed primarily to help visualize the orbits of comets At the bottom of the stereo display is a scale to control the amount of parallax to introduce The parallax is only introduced in the plane of the ecliptic This works well for low latitudes but has the odd effect of just moving everything as a whole when viewing from near the poles If you prefer focusing your eyes in front of the screen move the parallax control somewhat to the left if you prefer to relax your eyes and focus at infinity then move the parallax control to the right Page 11 2
125. h results in rational values for the scale factors If you zoom in enough to clearly see individual image pixels you can see that the coordinate system for image pixels puts the integral position in the center The statistics Size ofthe area under the glass Value and location of the center Value and location of the largest pixel under the glass Value of the minimum pixel Mean value of all glass pixels Median value of all glass pixels One Standard Deviation of the pixel values about the mean Page 10 22 Version 3 5 2 Sky View Below the statistics box you can optionally open windows that plot the row or column through the center of the glass The horizontal axis of each graph is in image pixels the vertical is in image pixel values This section may also be opened using the button in the right Sky View toolbar that looks Bd like a box containing a few stars much larger than the others However since the glass is useful in its own right the toolbar button only opens this section ifthe Image Tools window is already up Similarly closing this section does not also turn off the toolbar button 10 4 2 4 Region of interest This section lets you use the mouse to draw a rectangle over the abel 1426 FES SOOW x SH j ict j ithi j j Max 4 at 23 9 image and get statistics about the pixels within this region The Min ALCEO git aks area is the same one that can also be used to specify a region in Median 36498 StDev 117
126. he ROI toolbar button is On pressing and dragging the left mouse button draws a Region of Interest box This ROI can serve two roles One is a way to zoom Click on the ROI toolbar button then click in the Sky View with the left mouse button and begin to draw a box surrounding a region of interest When the button is released the ROI becomes fixed into position To perform the zoom press Zoom In in the tool bar the round magnifying glass with a within The current size position and ROI are saved and the Sky View is changed to expand the new area The Zoom Back tool bar button glass with a within then becomes available to restore the display to its previous size and position The Zoom In and Zoom Back buttons work as a pair for arbitrary levels of undo and redo This Zooming is implemented by actually sliding the scales around the edges of the Sky View just as if you had done it manually Thus the selected area may be rotated after the zoom due to a change in perspective in the map projection This is a feature The other use for the ROI is available only when an image is being display Basic statistics are computed for the pixels that lie within the ROI box and are displayed in the Images gt Processing tools window See it s help for details Also only while an image is displayed the left mouse button may be used to position a Magnifying glass graph the pixels along an arbitrary cross sectional slice through the image and comput
127. he next eyepiece These are shown in units of degrees minutes Below them is a toggle that will lock the two sliders so they move together This is to make it easy to create eyepiece shapes that are perfectly round or square As a special convenience there is a toggle which will create three open circles spaced to match the view through the venerable Telrad unit power finder The circles are 0 5 2 and 4 degrees in diameter As long as this special toggle is pushed in the other controls are made insensitive to avoid interfering with the preset values for the Telrad Next below are pairs of toggle buttons to select the Shape and Style of the next eyepiece Elliptical and Rectangular refer to circles and squares Solid and Outline refer to whether the shape will be filled in or just drawn as a border In the central portion of the Eyepiece window is a calculator that can be used to compute the sky angle of an optical system in two ways The first method uses the net focal length of the entire Page 10 16 Version 3 5 2 Sky View optical system and a linear size on the focal plane The technique is handy for CCD users who want to find the sky angle subtended by each pixel Another good use of this form is for photographers using film to find the amount of sky that will fit on their film To cover this wide range of applications the measures may be specified in any of several common units by adding the appropriate suffix Default units are shown in
128. he time interval between each step Choose from among the several handy intervals in the upper central radio box or choose Custom and enter any desired interval in the space provided It is okay to specify more than 24 hours to achieve intervals of several days It is also okay to specify negative values to run time backwards Version 3 5 2 Page 15 1 Trails Label This choice determines which intervals will to be label with a time stamp Choose from among several options in the upper right radio box or choose None if no labeling is desired Format This choice determines how to display each time stamp The lower left radio box offers either Hour Minute format or the current date Preference as set in the Preferences gt Date formats option in the Main menubar Font This choice sets the size of the annotation text font The bottom central radio box allows you to choose from several character sizes for the time stamps Start This choice specifies how the first time value is derived from the current XEphem time The lower right radio box offers several methods of determining the beginning of the first time interval Whole min rounds the current XEphem time forward to the next whole minute if necessary Whole day rounds to the next whole day Whole interval rounds to the next whole multiple of whatever time interval is set as specified in the Intervals choices Now means to begin with the current XEphem time without any initi
129. he values range from 20 at the top and 0 at the bottom Objects dimmer than the value specified are not shown Nominal celestial directions are indicated at the top and right edges Moons are displayed only if they are geometrically visible Use the top view to see whether they are also in sun light 6 3 2 1 Mouse functions The mouse may be used to identify any object in the Mars view Position the cursor near the object of interest and select the right mouse button A popup menu will appear with the objects name current location and magnitude 6 3 2 2 Control menu Field Stars This selection activates the Field Star setup window For more information about this facility see the Help for the Field Star window itself Telescope command This option causes the location of Mars to be sent to a fifo The intent is for the fifo to be connected to a telescope control process This mechanism is the same as that provided by the Telescope facility within the Sky view Please refer to its help for more details in 10 6 Movie Demo Page 6 4 Version 3 5 2 Mars View This option will set up the Main window time step controls for a 15 minute step size and start a loop which dramatically displays the motions of the moons as they orbit Mars This selection automatically disables the View gt Sky Background selection to insure reasonable speed Push the button again to stop the movie Close This removes the Mars moon display and
130. here Pref gt Zone does not update dates of FW NM if they happen to squirm constellation figures could stand some improvement length of night wrong when savings time causes dusk after midnight center constellation names based on boundaries rather than on figures solar trails don t account for long term 10 s of years precession changing font shrinks sky and Earth views unless their view has changed once plot s View settings are not Saveable trails are not always clipped properly against a user defined horizon alt az grid at dec 90 and v v is crazy use Crenshaw s method for more stable minimax solver algorithm Page 17 2 Version 3 5 2 Credits 18 Credits First and foremost many thanks to my wife Kathy for her unwavering trust acceptance and support aka Love Beyond that the following are in no particular order but all are greatly appreciated Thanks to Fridger Schrempp fridger schrempp desy de for his long term encouragement of the project and particularly for many suggestions to improve ease of use Thanks to Aaron Price aaronp mira aavso org for his work and enthusiasm to support accessing AAVSO data directly from within XEphem Earth satellite orbit propagation is based on the NORAD SGP4 SDP4 code as converted from FORTRAN to C by Magnus Backstrom b eta chalmers se See Spacetrack Report Number 3 Models for Propagation of NORAD Element Sets at http www celestrak com N
131. here in XEphem such as the Data gt Search window 13 3 During all this Marker on and off business there is no need to kill and restart x200xed it will just stand by for XEphem to reconnect Note The computer and the LX200 keep separate notions of time and Earth location The software makes no attempt to change these on either side The closer you make these in sync the more similar XEphem and the LX200 paddle will report information We have found that if the SIDE and LOCAL values on the paddle match the Sidereal time and Lat Long the time and date agree refraction is turned off in XEphem by setting an air pressure of 0 XEphem Epoch is set to 2000 and XEphem is set to update its time about every 2 seconds or so then the LX200 and XEphem will agree in all reported values to full display precision There will always be one difference however XEphem uses North as 0 degrees Azimuth whereas the LX200 uses South thus they will always differ by 180 degrees Page 16 2 Version 3 5 2 Notes 17 Notes 1 The program uses a horizontal plane tangent to the Earth Elev feet above sea level as the horizon for all altitude calculations rise set events etc Due to Earth s curvature this is not the same as the angle up from the local horizon unless the observer is directly on the ground The effect can be found from sin a 2 h 2 2Rh R h 2 where R radius of earth h height above ground same units as R a increase in
132. ically reset if the Scale is changed If the location is not near a feature then only location and solar altitude are displayed in the window The algorithm chooses the smallest and closest feature about which to report Activating the right mouse button while not over the lunar image but near a sky background object will bring up a popup menu containing the name and magnitude of the object One of the following two options will also be available Assign gt To ObjX To ObjY To ObjZ This cascade allows you to assign the given object to become ObjX Y or Z as desired 813 3 This will also cause all other views which are currently making use of this object to be updated and the object will be added to and selected by the Data table Also since this makes the object one of the User Defined objects it will now appear directly in the Sky View gt Locate pulldown menu Show in Data Table This option is only offered when the object chosen under the cursor is a planet the Sun or the Moon Selecting this option forces the object to be enabled in the Data Table The two features may be activated together if desired by first pressing the left button then the right button This is helpful when trying to locate a particular feature in the magnified view Try to always release the right button to dismiss the popup before releasing the left button If you release the left button before the right button the magnifying glass will remain on the i
133. ied in the Preferences A convenient button is provided to bring up the Date Table setup window Note that a column need not be printed to be used for sorting although it would seem unusual to do so The center section lists several fields that may used for sorting the list Pick each field in the order you wish to sort the list If you wish to make a change to the order you may Undo one at a time back to the beginning or Clear the entire sequence and begin again The bottom section is a text field which will show the results of the sort This text field is fully editable so you may delete specific objects add comments and so on as desired N B If you have chosen the edb format no checks are made that your edits have made the format illegal Version 3 5 2 Page 10 13 Sky View Pressing the right mouse button over the text field will bring up a popup menu if a valid object name is found at the beginning of the line under the cursor This popup has buttons to Delete the object on the current line from the list and Mark the object on the Sky View Across the bottom are several controls Save This writes the text field exactly as it now appears to the file named at the right of the format checked at the top N B No check is made that the format and the extension agree Sort This rebuilds the list according to the current settings Use this after changing something in the Sky View or after changing the format or sort settings he
134. igh plain 9 Planitia Low plain 16 Rupes rupes Scarp 7 Scopulus Lobate or irregular scarp Sulcus sulci Subparallel furrows and ridges 12 Terra Extensive land mass 4 Tholus tholi Small domical mountain or hill 2 Undae Dunes 81 Vallis valles Valley 1 Vastitas Extensive plain 128 Albedo Feature Ok Apply Toggle All None Close This brings up a separate window containing categories of surface features Buttons across the bottom allow turning all features on off or toggling Apply puts the choices into effect as will Ok which also closes the window Page 6 2 Version 3 5 2 Mars View More info This brings up a separate window with additional Mars information and control capabilities Please see the help from that window for more information Moon view This brings up a separate window which depicts the two Martian moons Please see the help from that window for more information 6 3 1 More info dialog Under Cursor Latitude N 9 05 Longitude 4 263 14 Sub Earth Lat N 24 00 Central M Long W 185 00 Seeing arc seconds 0 11 25 2000 18 46 11 UTC Apply Close Help The top portion of this window reports the location of the cursor as it is moved over the image if the left button is pressed The lower portion of this window shows the Martian latitude and longitude which currently face the Earth These values are computed each time an Update is performed from the Main Men
135. ile toggle the plot button back off to flush all data and close the file The windows that contain each of the fields used in the plot need not be visible while the plot is being generated Viewing plot files Existing plot files may be viewed by entering their name into the text field provided and selecting the Show plot file pushbutton As many different plot files may be viewed simultaneously as desired Each plot has separate controls for flipping the X and Y axes and for turning on and off a reference coordinate grid Control View 75 Sun Az and Alt at noon local time 42N latitude 70 65 60 55 50 45 40 35 30 25 20 170 178 184 The XEphem distribution kit includes a sample plot file of the analemma Page 12 2 Version 3 5 2 Tools 12 2 List values Select fields Create list file Include column headings List in LaTeX format File name home ecdowney xephem xepheml ist txt Title Close Help This window controls the list generation functionality of XEphem The fields you select define columns of a table written to a file as XEphem runs These columns look exactly like their corresponding fields on the XEphem windows and so are more familiar and readable than the entries in plot files They are designed to be used in further text processing operations or printed as is Two spaces are placed between each column Selecting data to list Select the Selec
136. ill be increased by 3 pixels This option also insures that even those moons which are dimmer than the limiting magnitude as specified by the scale to the right will be drawn with a circle of diameter 3 pixels Tags Selects whether to show the Roman numeral designation beneath each moon and a 1 arc minute scale calibration line Flip T B Flip L R These allow the scene to be flipped vertically and horizontally respectively 8 3 1 More info dialog From Earth 23 550 Tag Name ES Saturn f I Mimas 14 II Enceladus 1 1 III Tethys 4 IV Dione t 4 Vv Rhea T VI Titan EJ VII Hyperion 1 1 VIII Iapetus Ring tilt degrees front S Positions Saturn radii RA Y GS Z Gfront Moon x GE 0 000 0 000 2 869 0 308 3 835 0 513 1 804 1 798 4 844 1 477 5 588 2408 5 208 7 433 27 250 0 445 12 162 12 393 0 1 0 4 3 6 17 La 57 000 035 835 195 742 282 774 105 641 3 42 3 42 3 42 3 42 3 42 3 42 3 42 3 42 3 42 11 20 2000 16 56 07 UTC Close From Sun 23 823 36 92 34 97 39 52 38 14 40 21 40 71 32 71 55 41 28 67 NNN NNNNA Dec 19 19 19 19 18 18 47 20 19 21 13 3 16 4 18 5 31 58 28 1 19 4 nwoonn Mag 0 13 11 10 10 9 8 14 115 Do2ronwoooecon This button brings up a separate window which contains quantitative information about Saturn s moons and its rings All values may be used in pl
137. indow system and the various contributing organizations to the Open Software Foundation for Motif Their vision of network aware graphics is still unmatched Similarly will be forever indebted to all who contributed to UNIX My passion and appreciation for this remarkable operating system matured while enjoyed four wonderful years at Kitt Peak National Observatory now the National Optical Astronomical Observatory Tucson AZ in the early 80 s As with X UNIX plays a central role in my enjoyment of a career in scientific computing It was at KPNO where met the late Dr W Richard Stevens a fellow champion of the elegance of the UNIX architecture life long friend and mentor Special thanks to all the folks over the years who have provided innumerable ideas suggestions and bug reports both for XEphem and its ancestor ephem A major benefit to writing and distributing these programs has been the chance to make many friends from around the world Elwood Downey ecdowneyOClearSkyInstitute com Version 3 5 2 Page 18 5 Credits Page 18 6 Version 3 5 2 19 About Page 19 1 XEphem An Interactive Astronomical Ephemeris Program for X Windows Version 3 5 15 Oct 2001 Copyright c 1990 2001 by Elwood Charles Downey Permission is granted to use XEphem for personal use only If you have source you may modify it for your personal use but you may not distribute your changes nor use any portion original or modified i
138. information about these features The button in the upper left corner rather applies to both What and How Download DSS image However the toolbar down the right side is a little different These buttons share a broad common theme of affecting inspecting and deriving Where objects are located Some also effect how the mouse operates Because of their relatively complex nature these toolbar buttons are best Page 10 2 Version 3 5 2 Sky View described in their respective context so please see Help gt on Mouse and Image gt Processing tools for more information i Display cursor coordinates in corners as mouse roams over display Zoom in to region of interest only when ROI is defined a Zoom back to previous ROI only when zoomed in at least one level a Use mouse to draw Region of Interest El Mouse connected to magnifying glass images only La Mouse climbs to brightest pixel automatically images only Se Mouse draws cross sectional slice images only O Mouse computes 2D Gaussian fit images only A 3 o 10 2 Mouse functions The mouse serves many purposes in the Sky View Exactly what it does at any one time depends on whether it is located over an object and on the states of some of the toolbar buttons Idle Generally nothing happens when the mouse is over the Sky View and no buttons are being pressed However if the Roaming report toolbar button is On upper right basic data describing the position o
139. ion of the Sky image tools window can be opened by clicking on the button in the right toolbar that looks like a Gaussian graph or perhaps a large nose While measuring stars you might want to turn on the Jump to Max button on the right hand toolbar It is the one with the bright dot in the center to which a meandering arrow finally points When this button is on XEphem will begin at the pixel under the real cursor and walk the gradient to the brightest connected pixel All processing proceeds as though this brightest pixel is where the cursor really pointed 10 4 3 WCS Solver This window controls a pattern matching algorithm that attempts to register the star like artifacts in a FITS image with the entries in any or all of the XEphem Field Star catalogs currently including the GSC USNO PPM and Tycho star catalogs The choice of catalogs is controlled by the Control gt Field stars window Page 10 24 Version 3 5 2 Sky View RA H M S 03 19 42 000 Use field iOBTCTRA Dec D M S 41 30 00 00 Use field OBICTDEC Pixel right 0 000471976 Use field iCDELTI Pixel down 10 000471976 Use field iCDELT2 Rotate EofN 2 01406 Use field iCROTA2 Burned out 60000 S N ratio 5 0 Max pix acc 0 2 Min pix acc 4 0 Close Go Mark stars Help Rows 1 5 setting seed values The first five rows seed the search with approximate coordinates for the center of the image the scale of the image pixels in each direction and a p
140. iscussion here applies to all platforms See the Installation chapter for any issues on a particular platform Also refer to the Telescope Configuration window for configuration details 10 6 16 1 Disclaimer Before going any further we must make some things perfectly clear We believe the information provided here and the functionality provided by our software will perform in a satisfactory manner However CLEAR SKY INSTITUTE INC IS NOT RESPONSIBLE FOR ANY DAMAGE CAUSED TO YOUR EQUIPMENT UNDER ANY CIRCUMSTANCES WHATSOEVER USE AT YOUR OWN RISK We also wish to make it clear that this work was performed independently of and is not endorsed by Meade Instruments Corporation Their only contribution was to build a great amateur robotic telescope and provide for its computer control 16 2 Cable For handy reference below is a diagram showing the basic wiring of the cable between the LX200 RS232 port and a female DB9 connector suitable for connecting to COM1 on most PCs Note that although the the LX200 accepts a 6 pin connector the outter two leads are not used so a common telephone style 4 pin connector may be used RJ45 Looking down with clip beneath DB9 Female looking at finished end For more information try the following web sites http www2 crl go jp ka tnp meade cable html http www mapug com AstroDesigns MAPUG Battery2 htm anchor2189857 16 3 Routine operation With the LX200 powered and connected x200x
141. ite While downloading a file any set of lines found to match either format are extracted and saved to a file named the same as the last component of the URL except for changing the Page 13 5 Data extension to edb if necessary In this way XEphem automatically detects either format and derives a sensible file name Several particularly useful sites as of this build are already entered The first three are Dr TS Kelso s Earth satellite lists The other four are the Minor Planet Center s lists of hot comets and unusual asteroids During the download a search pattern may be entered to look for an object with a name containing the pattern Click on the Search option and enter the desired pattern The comparison ignores case and blanks If a match is found the entry is shown in the text block If more than one match the first is shown Regardless of whether any match the entire file is saved Whenever a valid object specification in either format is in the test box it may be assigned to User Defined Object X Y or Z by clicking the appropriate button The specification may be entered by hand or copy paste it need not have come from a downloaded file Special Asteroid files Special files created by the Minor Planet Center and Lowell Observatory may also be downloaded Each organization maintains extensive lists of all known asteroids and produces on a regular basis Keplarian orbital elements precessed to the current date Both ar
142. itial values of most options and settings from other entries in the resource file Settings which do not appear will use their internal default values 1 3 Windows Installation Executive summary 1 run setup exe taking all default values 2 reboot 3 double click the new XEphem shortcut on the desktop Long version XEphem must be installed by the Administrator or a user account in the Administrators group After installation if desired it is possible to allow multiple users to run XEphem so they each have their own separate workspaces while sharing the large support files and databases Details of sharing are be described in 1 3 3 Insert the CDROM and your computer should start the installation program automatically If it does not run the setup exe program by clicking Start gt Run then type d setup exe Change the letter d to whichever device Windows considers your CDROM drive The installation takes a while because of all the data being copied It also behaves a little unusual compared to most Windows programs One reason for the complexity is that really three programs are being installed XEphem is written for UNIX In order to run on Windows it requires a porting layer We have chosen the outstanding MKS Toolkit for Enterprise Developers see http www mkssoftware com Also required is an X Windows Server We have chosen the MI X server from Microimages see http www microimages com If you already happen to have
143. ition XEphem keeps this marker within the Sky View field of view at all times and will reposition the Sky View if necessary to achieve this On occasion this behavior can be annoying such as when you wish to use the Sky View for something not immediately related to the operation of the telescope In this case turn the marker off with this button and back on later as desired Enable Telescope GoTo This button controls whether the various controls throughout XEphem that command a telescope to move are in fact active These controls appear in the popup menu in the Sky View and in the various planetary closeup windows If you prefer these controls are disabled click this button off Another reason for this button is for those users of XEphem who have built their own telescopes with only encoders and no motors With a suitable driver XEphem can then show the location of the telescope in the Sky View even though it can not command motions Use no hardware test mode If this button is On when the telescope driver is started running then the driver is really started but it does not actually connect to the telescope In this mode the driver puts a marker on the Sky View at OH RA 0 Dec If you then place the cursor at some other location in the Sky View right click and release on Telescope GoTo the marker will move to this new location It is as though you are connected to a very fast telescope This mode verifies that all the software is runnin
144. itude distance from sun and earth light travel times heliocentric coordinates galactic coordinates ecliptic coordinates solar elongation angular size visual magnitude illumination percentage local rise and set times and azimuths local transit times and altitude length of time up constellation angular separations between all combinations of objects Local observing circumstance information includes Page 1 2 Version 3 5 2 Introduction UTC and local date and time local sidereal time times astronomical twilight and length of night local temperature and pressure for refraction elevation above sea level for parallax a monthly calendar RA Dec calculations may be topocentric or geocentric and apparent or astrometric When the Equinox is set to a fixed date the values are astrometric that is corrected only for precession and light travel time When the Equinox is set for EOD Equinox of Date the values are apparent and are also corrected for nutation aberration and relativistic deflection Topocentric values are further corrected for parallax augmentation and refraction XEphem can read databases of objects 13 The objects may be fixed specified via heliocentric elliptical hyperbolic or parabolic orbital elements to accommodate solar system objects such as asteroids or comets or specified via geocentric elliptical orbital elements to accommodate Earth satellites These are then available
145. izona edu for an improved version of anomaly c A great source of comet information is http encke jpl nasa gov Special thanks to Uwe Bonnes bon LTE E TECHNIK uni erlangen de and Ralphe Neill ran rdt monash edu au for their many ideas and support Many test cases were gleaned from the pages of Sky and Telescope C Sky Publishing Corp Most of the sample cities in the xephem sit file are from the xsat program which included the following notice Copyright 1992 by David A Curry Permission to use copy modify distribute and sell this software and its documentation for any purpose is hereby granted without fee provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation The author makes no representations about the suitability of this software for any purpose It is provided as is without express or implied warranty Most of the sample observatories in the xephem sit file are transcribed with permission from the table beginning on page 28 in the July 1993 issue of Sky and Telescope Any errors in transcription are strictly my own Page 18 4 Version 3 5 2 Credits Thanks to Lowell Observatory and the Minor Planet Center for maintaining their huge lists of asteroids See ftp ftp lowell edu pub elgb astorb html and hittp cfa www harvard edu cfa ps mpc html respectively Thanks to the National Space Science Data
146. ks to Every year or so it is adjusted via a leap second so it stays within 0 9 seconds of UT1 which varies continuously with the slight irregularities of the rotational motion of the Earth The UTC time The current Julian date to about 1 second accuracy The apparent sidereal time for the current time and location The local time zone name The name may be fixed to any short mnemonic Setting this manually turns off automatic computation of Daylight Savings Time When auto DST is on a small clock is shown at the top right of the Time section Hours local time is behind UTC i e positive west or negative east of Greenwich Setting this manually turns off automatic computation of Daylight Savings Time The local date This is UTC minus the value of TZ Offset The local time This is UTC minus the value of TZ Offset TT UT1 Number of seconds by which Terrestrial Time aka Ephemeris Time prior to 1982 leads UT1 TT is generally of interest when calculating the positions of solar system objects because it is a continuous time scale unaffected by the Earth s rotational vagaries The term Terrestrial means it is adjusted for the relativistic effects of gravity and the Earth s revolution around the Sun UT1 or UTC is of interest when relating those positions to the horizon to produce altitudes and azimuths The value may be computed automatically based on the current time or entered manually in which case it will not change The alg
147. l rising transit and setting conditions are accounted for and marked when they occur as in the following table Note that in the case of Earth satellites TODAY really means within the next 24 hours NoRise up some time but never rises as such TODAY NoSet up some time but never sets as such TODAY NoTran up some time but doesn t transit as such TODAY CirPol object is circumpolar never goes below horizon TODAY NvrUp object is never above the horizon TODAY The last column in the Data Table setup window controls for which objects angular separation is computed Each entry in the Data Table will be the angular separations between each pair of objects in degrees The vantage point for the Separation values depends on the Equatorial preference in the Main window Geocentric ignores local conditions and gives the separation as seen from Earth Page 3 4 Version 3 5 2 Data Table center Topocentric uses the local conditions known to XEphem The choice is particularly critical for lunar occultations and Earth satellites of course but the effect can be significant for the planets as well Geocentric separations between objects and the Sun will match the magnitude of the elongation given in the Data Table window When ObjX Y or Z are defined these will appear in the last column and separations between them and the other objects in column 1 may be selected for display Note Solving over a period that will include the
148. lay and Label One may now easily read off the local altitude of the Moon by comparing with the circles of 0 30 60 and 90 degree altitudes More precise values for altitude and azimuth may be obtained for any location using the right mouse button change Main location to Mauna Kea Observatory move cursor near southeast edge of Hawaii hunt around clicking right button until the popup says Mauna Kea slide down and let go over Point Earth gt Control gt Set Main the white Plus on the Earth should move over Mauna Kea and the central longitude should shift to approximately 155 degrees west Note the Latitude and Longitude in the Main view are also updated Zoom the view to show the sky from Hawaii Main gt View gt Sky View Sky View gt FOV gt 1 move left scale up until it says about 1 0 Sky View gt Locate gt Sun move cursor over the center of the Sun select right button pull down and let go over Track make sure Sky View gt Control gt Options gt Alt Az is selected or Main gt Preferences gt Equatorial gt Topocentric is set to get a topocentric point of view set up a movie showing the path of totality for the next two hours Main gt N Steps gt enter 24 then Enter Main gt Step gt 0 05 00 Main gt Pause gt 1 Main gt Update 2 7 3 Sky trail This example will use the Sky View to display a trail of the appulse between asteroid 121 Hermione and NGC 7293 which occurs about July 28 1995 We also demon
149. ld r normal 13 100 100 100 Font history bold ucidatypewriter medi um 12 Font pattern bold ABCDEFGHI JKLMNOPQRSTUYHXYZ abcdef ghi jklnnopqrstuvuryz 01234567890 25 un 1 Main Window This window lets you inspect and change many of the fonts used by XEphem The top scrolled list shows all fonts currently installed on your system Selecting one will copy the name to the Font pattern field and show a sample You can select with the mouse or by browsing with the Up and Down keyboard arrow keys Below that is a list of the fonts recently used in this window for convenient reuse if required Browsing operates the same way The Font pattern is a field in which a Font name may be entered including the splat character to serve as a wild card if desired Press Enter or the Search button in the Control menu to find and display a sample of the next matching font if any The font named here also applies to the menus of context controls described next The center menus in the menu bar across the top provide ways of referring to several font contexts The four toggle buttons just below the menu bar determines what happens when one of these context menu buttons is clicked as follows Get current When this toggle is active clicking a context menu button will cause the name of the current font for that context to be displayed in the pattern field and history list When this tog
150. lds above If a solution is found each star used in the solution will be circled and statistics about the quality of the solution will be presented The WCS fields that characterize the solution are written into the FITS header If you like the solution Save the image and this search will not be needed again Mark stars Clicking this button will draw a small circle around each group of pixels in the image the algorithm considers to be a star Use this to choose good values for Burned out and S N ratio Help Show this text 10 5 Locate menu This selection will pop up a list of the basic objects and the currently defined user objects if any Selecting an entry will place a cross hair over the object If the object is not within the field of view the Sky View will be moved so the object is centered If Alt Az mode is currently active and the object is below the horizontal the view will not be changed and a message will suggest the mode first be changed to RA Dec To aim the Sky View at any other object in the XEphem database please use Main gt Data gt Search 10 6 Telescope menu The Telescope menu in Sky View allows you to control any GOTO type telescope that is compatible with the venerable Meade LX200 Clicking on the top item in this menu will bring up a window for configuring and controlling the telescope connection Please see its own help for full details 10 6 Once XEphem is operating the telescope correctly it
151. lection tocal telescope xephem catalogs asteroids edb load Filter Shared Private Dir Dir This window allows you to load delete and inspect the collection of objects that are currently in memory These objects form what is referred to as the XEphem database The top section of the window displays a count of each major type of object and the total number in the database The counts do not include the planets Sun Moon or the user defined objects ObjX Y and Z The center section lists the catalogs which are currently loaded and the number of objects they contributed The objects loaded from a catalog may be deleted using the button to the left of the count This list may be saved at any time so this set of catalogs is automated loaded when XEphem starts To do so go to Preferences gt Save and Save the XEphem DBlnitialFiles resource under the Data Base category The lower section allows you to browse the directory structure on your system for database files in XEphem format and load them into memory See the README in the base distribution for a brief description of each catalog The Filter field sets the directory and file name pattern to qualify being included in the list of Files Any directory may be searched but handy buttons at the bottom right allow setting the directory to the values of the Shared and Private directories The Filter Version 3 5 2 Page 13 1 Data button in the lower center forces the directory given in the
152. lldown menu All Basic This pushbutton is a shortcut to turn on all the basic planets and user defined objects which are in the solar system Just S E ObjXYZ This pushbutton is a shortcut to turn on only the Sun Earth and any user defined objects which are solar system objects It does not effect whether the other database objects at large are displayed For that use the next control Version 3 5 2 Page 11 3 Solar System View All DB too This toggles whether all solar system objects in the data base are also displayed This is great when the asteroids database has been loaded In expectation of increased drawing time with all these objects when this option is on the scales switch so they only cause an update when they are released at their new net position Note these objects are never trailed If you want to include one of these objects in a trail first assign it to ObjX Y or Z Note Trail data is discarded at the time of the next Update from the Main window regardless of whether the object is displayed at that time or not 11 5 Scales The three scales at the edges control the position of the observer The vertical scale on the left controls the distance from the sun you are closer as the scale is slid further up The horizontal scale under the view controls the heliocentric longitude think of it as a rotation about the central axis The value of the scale is the heliocentric longitude towards you The
153. lliptical objects are characterized by 12 parameters the parameters that define a heliocentric elliptic orbit and the coefficients for either of two magnitude models These elements are the same ones often listed in the Astronomical Almanac The elements are in order i inclination degrees O longitude of ascending node degrees o argument of perihelion degrees a mean distance aka semi major axis AU n mean daily motion degrees per day e eccentricity M mean anomaly i e degrees from perihelion E epoch date i e time of M D the equinox year i e time of i O o g k or H G two fields to specify either of two magnitude models see below s angular size at 1 AU arc seconds optional Page 13 8 Version 3 5 2 Data You might have other parameters available that can be converted into these The following relationships might be useful P sart a a a p O 0 n 0 9856076686 P T E M n q a 1 e AU 149 597 870 km 92 955 621 U S statute miles where P the orbital period years p longitude of perihelion degrees T epoch of perihelion add multiples of P for desired range q perihelion distance AU Note that if you know T you can then set E T and M 0 XEphem supports two different magnitude models for elliptical objects One denoted here as g k is generally used for comets in elliptical objects The other denoted H G is generally used for asteroids in the Astronomical
154. m to be easily registered for use by these features This eliminates the need to make manual notes or perform data copy paste and allows the data to be available programmatically at various date and time settings 12 1 Plot values Select fields Create plot file Show plot file File name Browse home ecdowney xephem analemma plt Title Tag aK Je Close Help This window controls the plot generation and display functionality of XEphem You may select most numeric information displayed by XEphem in pairs to form x y coordinates of a plot You may select up to ten such pairs You then select a file to contain the plot information XEphem adds one line of information to the file for each x y pair each time iteration step XEphem can also plot any such file on the screen Selecting data to plot Select the Select fields toggle button to make each field in the other menus that are eligible for plotting appear as a pushbutton Select each such button as desired to form the x or y component of a plot As you make the selections they are listed in the menu You may also associate a one character tag with each line These tags will be included in the plot display for identification later Once all the field choices have been made you may return all the menus to their normal operational appearance by reselecting the same toggle button Specifying the plot file name Type the name of the file to be used to contain the plot informatio
155. mage If you run into this you can activate the glass again and mop up the remains of the old glass 4 2 Control menu Print This selection allows printing the current Moon view or saving it to a file Field Stars This selection activates the Field Star setup window For more information about this facility see the Help for the Field Star window itself 13 4 Set Earthshine This brings up a window containing a scale which allows you to set how bright the Earthshine is in the Moon image The value ranges from 0 black to 10 full sun light Full Page 4 2 Version 3 5 2 Moon View sun light is useful when you would like to peruse the Lunar surface but would rather not change the XEphem date to a full Moon This value depends on the gamma of your display A fine discussion of display gamma and a test image with which you can determine the gamma value of your own display may be found at the URL http www cs cmu edu afs cs cmu edu user rwb www gamma html Movie Demo This sets up an automatic display movie of the Moon This is done by setting the N Steps entry in the Main window to a large value setting the Step to two hours if Sky background is Off or to one minute if it is On and starting XEphem looping The movie can be stopped by selecting this option again or by selecting Stop from the Main window Close This closes the main Moon display and if open the More info window The image is never updated while i
156. mation on managing these special catalogs XEphem ships with a few perl scripts which might be helpful for converting databases in other formats into XEphem format These scripts are in the tools directory of the XEphem source distribution tree 13 2 Download Internet files Download a file containing edb or TLE formats Get http celestrak com NORAD elements stations txt Get http celestrak com NORAD elements science txt Get http celestrak com NORAD elements amateur txt Get http cfa ww harvard edu iau Ephemerides Comets Soft03cmt txt Get http cfa www harvard edu iau Ephemerides CritList SoftO3critList txt Get http cfa www harvard edu iau Ephemerides Distant SoftO3Distant txt Get http cfa www harvard edu iau Ephemerides Unusual Soft03Unusual txt Get f Search during download for ao 10 edb or TLE spec Erase Assign to ObjX ObjY Objz 740 10 1 14129U 830588 01283 16929832 00000147 00000 0 10000 3 0 8428 2 14129 26 2869 248 8225 6028608 189 6254 149 3718 2 05867567109849 Download large daily epoch asteroid data set Get from Minor Planet Center saved in AstMPC edb and AstMPC_dim edb Get from Lowell Observatory saved in AstLowell edb and AstLowell_dim edb Close Help Version 3 5 2 This window provides an easy means to download any file which contains objects defined in either XEphem s edb format or the NORAD 2 Line Element TLE format commonly used for Earth satell
157. mb ready to emerge To see it press Main gt Update to advance the time by 1 minute Spica appears at 11 47 and near the craters depicted in the schematic on page 83 An analytical method is to use the Main gt Tools gt Solve method to find the time when the following equation evaluates to zero Spica Moon Moon Size 7200 Set the Desired Accuracy to 0 0 1 and one finds the occultation occurs at 11 46 10 UTC 2 7 8 International Space Station This example will show how to display the ground track for the International Space Station in the Earth View find when it will next be visible in your location and display its path through the sky overhead in the Sky View First be sure XEphem has a working connection to the Internet click Main gt Network Setup click on the appropriate choice Get fresh elements from the web bring up Main gt Data gt Download Internet files Type ISS in the Search field and turn on the toggle click Get next to the entry for stations txt click Assign to ObjX Show the current position of the ISS in the Earth view bring up Main gt View gt Earth then Control gt Objects click the left menu button at the top slide down to ISS and release Create a ground track for the next few hours click the Trail button in the column used for ISS slide Number of tick marks to about 50 select Orientation gt Up Font gt Small click Apply For fun show in mission control format click Earth
158. mple Proceed to install XEphem Version 3 4 y n y The possible responses are to type y or n followed by Enter Enter alone will be the same as y Follows is some commentary on the various questions asked by the install script in the order in which they appear 1 You are asked to confirm you really do want to install XEphem and if so are asked to agree to its licensing terms Answering n to either of these will end the installation with no change to your system 2 You are asked to specify several directories In most cases the defaults offered should work fine However in deference to local customs the installation allows you to change them if desired Basically if you do not know the significance of a directory take the default Application defaults a very small file will be created here so xephem can know your choice for the Base Installation directory see next Base installation this will contain all the supporting files needed by xephem at runtime including all the catalogs This must have at least 200MB free for a basic installation or 800MB if you choose to also install the USNO catalog described shortly All files in this directory are used read only by XEphem and can be shared among all users If you have installed XEphem before and you elect to use the same Base directory some files will be added and many files will be overwritten The install script makes no attempt to clean out deprecated files or preserve files
159. n in the text field provided When XEphem first needs to write to the file it will first check for the existence Version 3 5 2 Page 12 1 Tools of the file and if it already exists ask whether you wish to append to the file or overwrite it A leading in the filename will get expanded to the value of your HOME environment variable Specifying a plot file title Enter a short title for the plot information in the text are provided When XEphem first writes to a plot file it will place the contents of the title text area if it is not empty into the file as a comment All lines within a plot file that do not begin with an alphanumeric character are considered comments and are ignored If the first line of a file is a comment XEphem will use it as the title for the plot when it displays the plot Generating the plot entries Once the fields have been specified and the plot file named and titled you may select the Plot to file toggle button when ready Now each time XEphem goes through one iteration the values you have selected and their tags will be written to the plot file Note that when plotting is activated XEphem does not update the screen until the N Steps count goes to 1 This greatly speeds the creation of plot files by avoiding screen updates If you wish to watch each iteration set N Steps to 1 and select the Update button manually for each iteration Once all the desired data has been entered into the plot f
160. n other programs Contact the author to discuss commercial classroom or other situations NO REPRESENTATION IS MADE ABOUT THE SUITABILITY OF THIS SOFTWARE FOR ANY PURPOSE IT IS PROVIDED AS IS WITHOUT EXPRESS OR IMPLIED WARRANTY If you are using the free version check out the CDROM version Available for UNIX Windows and Mac OS X Easy installation 600 MB more data Priority email support Comprehensive printed User Manual RARA AA Stay in touch with XEphem at http www ClearskyInstitute com xephem Clear skies Elwood Downey ecdowney ClearSkyInstitute com Ok About Version 3 5 2 LST O 2 4 edb 10 13 13 3 hzn 10 14 2D 10 23 AAVSO 10 5 12 10 aberration 12 1 About 19 1 accuracy 12 5 17 1 Administrator 1 6 airmass 3 2 Alt 3 2 Alt Dec 10 29 analemma 12 2 anomaly 13 4 Apollo 4 4 apparent field 10 17 argument of perigee 13 5 argument of perihelion 13 8 13 10 ascending node 13 4 ASP 13 12 Assign gt 4 2 10 6 11 1 asteroid 2 18 Astronomical Almanac 12 1 astronomical calculator 12 5 Atm Pressure 2 2 AU 3 3 Authorization 1 6 1 7 Auto refresh 12 12 Autosave 2 10 Autoselect 2 9 Az 3 2 Az RA 10 29 Backward 1 2 4 Bayer 10 11 BC 1 12 Bell 2 7 below the horizon 10 29 berkeley 12 11 BITPIX 2 19 10 19 Boundaries 10 11 Brighter 10 21 brightest pixel 10 20 Brightness 10 21 browsing 13 2 BSCALE 10 19 Bugs 17 2 Bureau of Longitudes 12 1 Burned out 10 25 calculato
161. names in XEphem will appear somewhat different than they normally do under Windows Drive letters are changed from x to x and backslashes are changed to forward slashes So for example the following file name in normal Windows c program files clear sky institute inc nutc auxil will appear as follows inside XEphem c program files clear sky institute inc nutc auxil This only refers to places where XEphem displays a file name In most cases throughout XEphem where you are asked to enter a path name you may use either naming strategy 1 3 5 Printing XEphem performs all printing using high quality Postscript format but printers typically found on Windows computers do not directly support this format We could have included a nice commercial Postscript printing package on the XEphem distribution and passed the licensing cost on to you Instead we noted that same package can be downloaded off the Internet at no charge for personal use So you save money by performing the installation yourself as follows 1 Go to http www ghostscript com Look for and go to the link at wisc edu Download the latest release of AFTL Ghostscript not GNU Ghostscript You do not need ghostview just ghostscript As of this writing the latest version is 7 00 located at ftp mirror cs wisc edu pub mirrors ghost AF PL gs700 gs700w32 exe This is known to work well with XEphem 2 Install ghostscript according to its instructions Basically just run the exe B
162. ndow allows you to define a proxy or SOCKS server to use for the various XEphem features that utilize the Internet One of the following three choices must be enabled for Internet access to be available Direct connect This choice just means to use the direct DNS IP TCP IP sockets as necessary Use this one unless you are behind a firewall via Proxy This choice attempts to access the Internet via a Proxy Type the port address and the host name of the proxy in the field provided via SOCKS This choice attempts to access the Internet via a version 4 SOCKS server Type the port address and the host name of the server in the field provided These values can be initialized using the environment variables SOCKS_PORT and SOCKS_NS 2 1 2 External Time Loc File name home ecdowney xephem external txt OK Cancel Help XEphem can read a file or fifo containing sets of time latitude and longitude values and automatically install these values sequentially unattended Enter the name of the file in the window and press OK To pause between updates set the desired delay in the Pause field of the Main window All features of XEphem such as plotting and listing are available while this feature is running 12 Version 3 5 2 Page 2 5 Main Window The format of each line of the file is as follows JD Lat Long where JD Julian Date Lat Latitude radians north Long Longitude radians west The fields are separated
163. nitudes are shown to the right of the name surrounded by parentheses Magnitudes are shown to the nearest 1 10 with the decimal point removed Other labeling facts Trailed entries do not contribute towards the brightest count The Persistent Label option for individual objects is never disabled Greek characters are used in Bayer names when YBS edb is loaded 813 1 Version 3 5 2 Page 10 11 Sky View 10 3 2 Filter Solar System Galaxies Toggle Toggle Planets G Spiral Elliptical H Spherical Hyperbolic 4 Clusters Parabolic Nebulae Earth Sat Toggle Clusters N Bright Toggle F Diffuse C Globular K Dark 0 Open P Planetary U in Nebula stars Other Toggle Toggle S Single Q Quasars B Binary L Pulsars D Double J Radio M Multiple R S N Rem Y Variable Undefined T Star like 7 Sol Sys Lim Mag 1 Mag dot step 3 Stars Lim Mag 4 Deep Sky Lim Mag Ok Apply Toggle All Reset Close Help This window lists all classes of objects supported by XEphem Using the Filter window one may select which classes of objects are displayed on the Sky view window For reference the Filter window also contains the schematic symbol for each type of object and its code when used in a database file The symbol displayed for each class of object is that which will be used to represent the object in the Sky view unless Just dots is selected Three scales near the bottom of the Filter window control the faintest magnitude limit to
164. ns with Data Table setup 278 15 58 26 58 03 Variable 260 58 59 63 35 50 Variable Hamal ari 4ur Iota 3 Aur Name ns RA Dec Az Alt Type Sky List Topocentric Mean place Epoch 2000 00 11 26 2000 8 47 59 U Name Cns RA Dec Az Alt Type Alpheratz And 0 08 23 30 29 05 26 0 300 33 44 9 52 52 Double S ISS ZARYA And 0 27 20 88 23 37 36 1 293 34 02 9 14 44 Earth Sa Mirach And 1 09 43 90 35 37 14 0 297 15 28 23 57 58 Multiple And Gammal 57 And 2 03 54 00 42 19 47 0 297 32 23 36 24 38 Multiple Sheratan Ari 1 54 38 40 20 48 29 0 277 52 52 23 03 22 Variable 2 07 0 4 56 D Save Sort Close Help This window lists sorts and allows saving the objects currently displayed in the Sky View to a file Basing the list on the Sky View means the selection criteria uses the power of the Options and Filters controls as well as the region of the sky as defined by the center and field of view If you wish to include all objects without regard to position use the Cylindrical project mode set RA Dec FOV 180 Dec 0 and resize the Sky View window to show the entire universe At the top the format of the file created may be specified in either of two formats The edb format saves the objects in the XEphem catalog format This is handy for using the XEphem filtering options to create custom catalogs The text format is a columnar listing The columns that are printed are the same as those currently selected in the Data Table printed to the precision specif
165. ommensurate with the current Longitude Local Sidereal Time at next local Midnight as per the time zone Looping see also 1 5 1 1 Now Step N Steps Pause Site name These are shortcuts to go backwards or forwards by one Step Can also be performed by typing Control b and Control f Clicking this button will synchronize XEphem to the computer clock and commence Updating every Pause seconds If Pause is 0 when this is started it will be set to 10 seconds This is really just a shortcut to clicking Now under the calendar setting Step to RT Clock N Steps to something large and then clicking Update The amount of time UTC and its derivatives is incremented each loop The number of times the display will be updated time advanced by Step each step automatically Number of seconds to pause between screen updates This is used mainly to set up for free running unattended operation Pausing is not done when plotting or solving is active When looping time is maintained at a whole multiple of pause length Above the Latitude field is an button which can display the current site name Pressing this button will bring up a list of cities and observatories The list is from the file named xephem sit in the shared directory Click on one entry in the list then press Set to set the Name Latitude Longitude Elevation and Time Zone fields in the Main window The same may also be done in Version 3 5 2 Page 2 3 Main
166. only if they are geometrically visible from Earth Use the top view to see whether they are also in sun light The default longitude of the GRS is set to 61 degrees where it was in late May of 1997 This may be changed interactively in the More Info window Version 3 5 2 Page 7 1 Jupiter View 7 1 Mouse functions The mouse may be used to identify any object in the Jupiter view Position the cursor near the object of interest and select the right mouse button A popup menu will appear with the objects name current location and magnitude 7 2 Control menu Print This selection allows printing the current Jupiter view or saving it to a file Field Stars This selection activates the Field Star setup window For more information about this facility see the Help for the Field Star window itself 13 4 Telescope command This option causes the location of Jupiter to be sent to a fifo The intent is for the fifo to be connected to a telescope control process This mechanism is the same as that provided by the Telescope facility within the Sky view Please refer to its help for more details in 10 6 Movie Demo This option will set up the time step controls in the Main window for a 15 minute step size and start a loop which dramatically displays the motions of the moons as they orbit Jupiter This selection automatically disables the View gt Sky Background selection to insure reasonable speed Push the button again to s
167. open Views gt Sky View gt Telescope gt Configure 2 Edit the field Serial Device so it contains your appropriate name 3 Now again from Main open Preferences gt Save and click on Save That s it The chapter on LX200 now applies see 16 1 5 Operation XEphem starts by showing the Main window with each parameter set to its default value The parameters on the Main window are primarily devoted to describing the location and time for which all other data in XEphem are computed You can change this time manually and press Update and all other windows throughout XEphem will be recomputed Or you can start a loop that steps time each step automatically by an amount you specify There are three fields that control this looping behavior Step is the amount of time to add each step or after one Update Page 1 10 Version 3 5 2 Introduction N Steps is the number of steps to run in a loop Pause is the amount of real seconds to pause between steps When looping is in effect the bottom button on the Main window says Stop When the number of steps goes to 0 or the Stop button is selected the looping stops and the button label changes back to Update A common mode is to have XEphem automatically stay in sync with the computer clock This can be done as follows set Step to RT Clock set N Steps to a large number say 1000000 set Pause to the desired update time say 10 seconds click Now under the calendar click
168. orithm uses values tabulated in the Astronomical Almanac for years 1620 0 through 1998 0 and is accurate to within a few seconds over that interval Dates prior are Version 3 5 2 Night Sun Dip Dawn Dusk Length LSTOO Main Window from Stephenson and Morrison or K M Borkowski with an estimated error of 15 minutes at 1500 B C A linear extrapolation formula predicts future values The number of degrees the Sun is below the horizon that we wish to call twilight Common definitions include Civil Sun 6 degrees down headlights barely show on pavement Nautical Sun is 12 degrees down sky and ocean merge Astronomical Sun is 18 degrees down dark as it gets The Sun Dip setting applies to the following fields Local or UTC time when the Sun center is Sun dip degrees below the horizon before sunrise today Local or UTC time when the Sun center is Sun dip degrees below the horizon after sunset today Length of astronomical night i e Dawn Dusk If this and the display for Dawn and Dusk are shown as it means the Sun is either always below or always above Sun dip degrees below the horizon on this particular day N B These three fields always apply to the local current day Difficulties arise when these events occur within 4 minutes of local midnight with respect to the time zone defined by TZ Offset In particular if these fields are not behaving as you would expect check that the TZ Offset is set c
169. ossible rotation The center must be known to within about one half the smaller of the image width and height The scale must be known to within about 10 The rotation seed need not be accurate at all but better estimates will result in vastly faster solution times Indeed better values for any field will improve the solution speed and also reduce the chances of a false solution Each of the fields may be typed or pasted into the fields down the left But often FITS files will include fields which contain information suitable for this purpose In the column down the right you may enter the names of such fields Clicking the Use field button in a row will read the value from the header field named on the right and install it into the field on the left of the same row possibly after some reformatting and change of units Certainly not all forms are supported so please take care to check for proper units and formatting yourself The default fields supplied are fairly common and are known to work if you are lucky enough to have them in your images Row 6 scanning the image for star like artifacts The next row contains two parameters which control the algorithm that scans an image to extract what seem to be reasonable candidates for stars that presumably will also be ina Field star catalog Burned out This parameter sets the largest pixel value in the range 0 65535 a star may contain Groups of pixels being considered as a candidate star by
170. otting listing and solving The E and S columns are 1 if the moon is visible from the Earth and Sun respectively Version 3 5 2 Page 8 3 Saturn View The ring tilt is displayed as the angle above or below the line of sight to Saturn from the Sun and the Earth A positive value means the front of the rings are tilted southward The locations of the moons are given in two coordinate systems The first three columns are the displacements of the moons in Saturn radii with respect to the celestial plane The next two columns give the RA and Dec location of the moons in the current equinox as specified on the Main window Page 8 4 Version 3 5 2 Uranus View 9 Uranus view Siik Pole View unlig terminator i ne Orientation gr BE Earth Control view Help Earth View 5 Moon with standard tag 18 Pa Limiting Zoom pt magnitude e E Image i scale Y I Equatoral orientation nd qs IY 8 21 2001 23 26 12 CDT This is a schematic view of Uranus and its moons at the indicated date and time In addition background sky objects may also be displayed The scale at the left controls relative magnification The scale at the right controls the dimmest magnitude which will be displayed Uranus is always displayed The values range from 20 at the top and 0 at the bottom Objects dimmer than the value specified are not shown Nominal celestial directions are indicated at the top and right edges
171. ou for using XEphem 1 1 Summary of Capabilities XEphem is a scientific grade interactive astronomical ephemeris package computes heliocentric geocentric and topocentric information for all objects has built in support for all planets the moons of Mars Jupiter Saturn Uranus and Earth central meridian longitude of Mars and Jupiter Saturn s rings and Jupiter s Great Red Spot allows user defined objects including stars deepsky objects asteroids comets and Earth satellites allows user defined objects including stars deepsky objects asteroids comets and Earth satellites offers many large databases including Tycho Hipparcos GSC USNO displays data in configurable tabular formats in conjunction with several interactive graphical views graphically displays a 24 hour period showing when any selected objects are up displays 3 D stereo views of the Solar System that are particularly well suited for visualizing comet trajectories quickly finds all close pairs of objects in the sky sorts and prints all catalogs with very flexible criteria for creating custom observing lists can create plots of any pairs of all data fields throughout the program downloads AAVSO light curves directly online downloads current asteroid and comets lists from Lowell and MPC downloads timely Earth satellite orbital TLE parameters downloads Digitized Sky Survey FITS files from STScl or ESO Version 3 5 2 Page 1 1 Introdu
172. ources will be considered up to date even if they were not selected to be written to the resource file N B The values saved are as they appear in this window which may be different from their current value if they have changed since the last Refresh Refresh Updates the changed and save status of each resource in this window Each Major resource found to be out of date is selected to be saved by default This refresh action also happens automatically after a Save is performed and just before the automatic Saving if AutoSave is on when quitting Close Closes the Save window Help Shows this information Page 2 10 Version 3 5 2 2 5 2 Save Fonts Action to perform when a selection is made from a pulldown menu P Se Scrolled list of all available fonts ere List of fonts previewed in this session En Font name or pattern for which to search EN Sample of font selection mn Control Buttons Text Other Help Set action first Get current Set Get default Restore default Then choose target from menus above 411 available fonts j1s fixed medi um r no rmal 16 1 50 75 75 c 160 315x0208 198 jis fixed nedi um r no rmal 24 1 70 1 00 1 00 c 240 315x0208 1 jis fixed nedi um r normal 24 230 75 75 c 240 j15 x0208 198 mmni sc fi xed bol d r normal 0 0 75 75 lt 0 1508859 1 i i xed bol d r normal 5 is088 ixed bol d r normal 1 3 1 00 1 00 100 0 ixed bo
173. p view Selects whether to also display another window looking down on the Uranus system from above the N celestial pole This window will tend to remain aligned above the main view when either is resized Moons are displayed only if they are in sun light Sky background Selects whether to also show objects within the current field of view that are in the XEphem database memory or available from the Field Star facility The size of the object is determined by the limiting magnitude as specified by the scale at the right Objects are drawn using the same symbols as used by the Sky view While this option is on XEphem will continue to retrieve field stars as required Page 9 2 Version 3 5 2 Bright moons Uranus View If this option is in effect then the diameter of all moons will be increased by 3 pixels This option also insures that even those moons which are dimmer than the limiting magnitude as specified by the scale to the right will be drawn with a circle of diameter 3 pixels Tags Search whether to show the Roman numeral designation beneath each moon and a 1 arc minute scale calibration line Flip T B Flip L R These allow the scene to be flipped vertically and horizontally respectively 9 3 1 More info dialog Moon Positions Uranus radii RA Tag Name Uranus I Ariel E 1 0 000 0 000 0 1 II Umbriel 1 1 1 1 S 1 1 735631 5 103 4 1 2 604 8 439 6 III Titania 1 IV Oberon 1 Vo Miranda 1 8
174. pper limb or center of the object sets TODAY See note below for Earth satellites HrsUp The number of hours the object is up TODAY that is the difference between the set and rise times See note below for Earth satellites Note for time zones Rise and set circumstances are all computed in local time Ifthe Time zone preference from the Main menubar is set to UTC then the times are converted to UTC Thus when reference is made to TODAY it means the current local date not UTC date Note for Earth satellites Due to their generally rapid motions Earth satellites often have many rising and setting events per day For this reason the rise and set time for satellites are not restrained to be during the current local day Rather for satellites XEphem displays the very next rising and setting events that occur strictly later than the current time on the Main window provided they occur within 24 hours This means that if the rise or set time displayed is earlier than the current local time on the Main window it actually refers to the next day This doesn t happen for the other objects because their times are restricted to events that happen just today Similarly we can only compute the HrsUp column if the set time is strictly later than the rise time The upshot of all this is that the best way to really understand the visibility of a satellite in your area is by graphing its altitude over the desired time interval Various odd bal
175. quency Doppler CPU time Progress Remaining Close Elwood C Downey ecdowney clearskyinstitute com Tue Aug 31 23 49 31 1999 GMT 279 days 13 45 25 322 sent Tue Nov 28 04 50 32 2000 GMT D4oc00ab 5081 4144 840898 16 Thu Oct 5 00 52 24 2000 GMT R amp 20 56 42 Dec 10 01 12 301420 1 42015625000 GHz 8 59746 Hz sec 9 01 42 32 43 18 48 42 Help This window can read and interpret the various log files which accompany the SETI home client version 2 and 3 For full details about this remarkable project see http setiathome ssl berkeley edu Enter into the text field at the top the path to the directory in which the setiathome client is running The controls operate as follows Refresh Reread the log files in the SETI home directory specified about and produce a new report An error is reported if any of the required files can not be read Sky Point Version 3 5 2 Page 12 11 Tools This will center the Sky View at the position of the work unit currently being processed It also assigns the location of the work unit to user definable object OBJZ doing so will add it to the Locate pulldown menu of the Sky View and add it to the View gt Data table for easy reference Sky Mark This will mark the position of the work unit currently being processed on the Sky View but only if it is already within the Sky View field of view The Sky View is never re aimed with this command This always also assigns the
176. r 12 5 Calendar 2 3 Canonize 12 13 caret 13 7 catalogs 1 8 CDELT1 10 24 celestial 4 1 classes 10 12 Version 3 5 2 Index Index close pairs 12 7 cloud cover 5 6 Cns 3 2 Colors 2 12 COM1 16 1 Compiling 12 4 Confirmations 2 8 Constellation 10 11 Context 2 1 continent outlines 5 6 Contrast 10 21 Control process 10 27 Coordinate Converter 12 12 copy paste 12 1 Create Trail 11 2 Credits 18 1 current working object 13 7 Cylindrical 5 5 cylindrical 5 5 Cylindrical 5 6 Darker 10 21 Data 13 1 Data Table 3 1 database 13 1 Dates 1 12 Dawn 2 3 DB Fifo 13 2 DB9 16 1 DBlnitialFiles 13 1 DE200 12 1 Dec 2 7 decimal year 1 12 Declination 3 2 deflection 12 1 Delete all 13 2 DeltaT 2 2 dimmest pixel 10 20 Disclaimer 16 1 diurnal motion 10 29 DNS 2 5 dots 10 12 Download 2 6 drag 13 5 DSS 10 19 Duller 10 21 duplicates 13 14 Dusk 2 3 Earth satellite 13 5 Earth satellites 3 4 13 11 Earth satellites parameters 13 11 Earth view 5 1 Earthshine 4 2 eccentricity 13 4 13 8 13 11 eclipse 2 16 5 1 10 9 ecliptic 3 3 Ecliptic 10 10 11 3 Elevation 2 2 2 14 elliptical 13 4 Page l 1 Index Elliptical 13 8 Elliptical objects parameters 13 8 English 2 7 Epoch 2 2 3 2 EPOCH 10 19 Equatorial 10 10 equinox 13 4 13 8 13 10 ESO 2 20 13 13 Examples 2 14 External Time Loc 2 5 eyepiece 10 5 Eyepieces 10 10 10 16 Feature labels 6 3 Field Stars 13 11 fifo 2 5 fifos 1 8 File forma
177. r in all copies and that both the copyright notice and this permission notice appear in supporting documentation All work developed as a consequence of the use of this program should duly acknowledge such use No representations are made about the suitability of this software for any purpose It is provided as is without express or implied warranty IC edb was submitted by Christos Siopis siopis astro ufl edu Constellation algorithm is from a paper by Nancy G Roman Identification of a constellation from a position Publications of the Astronomical Society of the Pacific Vol 99 p 695 699 July 1987 Further contributions from Chris Marriott and Ernie Wright The list of boundaries is derived from the three files constell 1875 data constell 1875 hdr and constell doc at ftp explorer arc nasa gov pub SPACE FAQ New version of Gemini constellation by Lutz Maendle Imaendle csi com Thanks to Dr Harald Fischer fischer vs ulm dasa de for the GPS awk routine and sample position database The high precision precession routine is from 1989 Astronomical Almanac as interpreted by Craig Counterman Mr Counterman also deserves the credit for providing the initial encouragement to write an astronomical tool specifically for X Windows back in 1990 and for significant assistance while developing the heliocentric models The Earth map is derived from data supplied with xearth which included the Version 3 5 2 Page 18 3 Credits
178. re Close Closes this window Help Shows this help 10 3 5 Horizon Choose method for specifying local Horizon Fixed displacement Degrees above horizon 0 Horizon profile map file name Browse home ecdowney xephem sample hzn Close Help XEphem allows you to choose between two ways to display your local horizon One way the simplest is to define one altitude that will be used at all azimuths To use this method type the desired altitude in the field provided then press Enter or toggle the button On The other is to create a file containing a table of the altitude and azimuth around your entire horizon To use this method type the name of the file containing the table in the text field provided then press Enter or toggle the button On The Browse button will bring up a File Selection Dialog for convenient interactive selection of available files if desired This is handy if you find yourself setting XEphem to one of several different Sites and you have a horizon table prepared for each The Horizon profile file format suffix hzn and its use by XEphem are defined as follows Page 10 14 Version 3 5 2 For example 0 20 50 100 180 182 185 300 10 15 25 20 25 45 10 15 Sky View Each line should contain exactly two numbers separated by spaces The first number is the azimuth expressed as degrees East of North The second number is degrees above horizontal Lines of any other form are ignor
179. re that has been created for XEphem This information is not necessary for typical operation so you may skip this for now and come back some day if you are curious Version 3 5 2 Page 1 7 Introduction If XEphem is installed in the default location the following directory structure is created c Program Files Clear Sky Institute Inc nutc bin auxil catalogs fifos fits XEphem XEphem contains files specific to each user such as preferences plots and lists Initially it contains one file XEphem a file containing a few default values different from those built within the program If a change is made and saved as a new Preference setting it is recorded in this file Nutc contains all files that can be shared among all users Some of these are described below bin contains the binary executable files for XEphem itself and some auxiliary command line tools such as the driver for using XEphem with LX200 compatable telescopes and programs for updating the asteroid databases The installation process adds this directory to global PATH Later in the XEphem documentation where it refers to the tools directory it really means bin in the Windows version auxil contains supporting files such as planetary images observing sites help text and certain ephemeris data catalogs contains object databases in XEphem s edb xe2 and gch formats The Hubble Guide Star catalog is in catalogs gsc and the USNO SA2 0 if installed is in c
180. rise or set times of either object is generally better performed from the geocentric viewpoint The refraction effect of the topocentric viewpoint causes many arc minutes of rapid whiplash displacement as the objects rise and set that overlays the smooth celestial motion of the objects This rapid position variation can confuse the solver algorithms that expect fairly smooth functions Version 3 5 2 Page 3 5 Moon View 4 Moon view This is an image of the Moon shaded to indicate phase It may be flipped and scaled as desired and many Lunar features may be labeled including most spacecraft landing sites During a Lunar eclipse the edges of the umbra and penumbra regions are drawn as solid and dashed lines respectively Control View Scale Help El Apollo 15 Apollo 1 o Apollo 11 pollo 13 14 2 pollo 16 11 20 2000 7 56 07 UTC The coordinate system on the Moon is such that latitude increases towards the north and longitude increases towards the east When facing the Moon with the unaided eye lunar east is towards the right The lunar image in XEphem is oriented with the polar axis vertical on the screen Letters are placed at each edge of the image to show nominal celestial directions If at least three colors can be allocated the image is rendered with at most 30 shades of gray if only two colors can be allocated it is dithered into a black and white image The Moon nods and rocks slightly as it moves
181. rols are being slid or whether the graphics are not redrawn until the mouse is released The decision depends on the speed of the computer display and data bandwidth If the system is fast enough turning this on can produce dramatic results Horizon map This controls whether to overlay the local horizon profile on the Sky View and when in Cylindrical Alt Az mode whether objects below the horizon are drawn The profile is drawn at azimuth steps of 1 degree See Options gt Horizon gt Help for more information 10 3 5 Constellation Boundaries This toggle controls whether constellation boundaries are shown Figures This toggle controls whether constellation figures are shown Full Names This toggle controls whether full constellation names are shown The names will be centered within the extent of the constellation figure This control and Abbreviations can not be both on at once Abbreviations This toggle controls whether abbreviated constellation names are shown The names will be centered within the extent of the constellation figure This control and Full Names can not be both on at once Labeling This portion controls labeling options The three sliders select how many of the brightest objects to label in each of three categories The label itself may consist of the Name or Magnitude or both depending on which of the two buttons are depressed adjacent to each scale If Names and Magnitudes are both enabled then the mag
182. rotate about the pole when moved left and right or about a horizontal line centered on the window when moved up and down If your system is sufficiently fast the effect in quite dramatic Page 5 6 Version 3 5 2 Mars View 6 Mars view Control View Help Equatorial directions Sunlight terminator Viking albedo A 1 REY image morphed A O ee er to current Earth ae A y Be Bavorisl ns SW view is Tharsigjontes 7 Echus Montes A Ascrangs Mons ebus Montes O Snow Hundreds of I features Ni including lander sites 8 18 2001 5 26 12 CDT This window displays an image of Mars as it currently appears from Earth center The resolution is 2 3 degree per pixel The orientation is always parallel to the Martian rotation axis The NSEW markings are directions on the celestial sphere 6 1 Mouse functions Left Button If the View gt More Info window is open then moving the mouse around over the image while holding the left button will display the Martian latitude and longitude under the cursor location A magnifying glass also appears attached to the cursor Right Button Pressing the right button while over the planet will present a popup menu Sliding down and releasing on the Point button in the popup will reposition the view so the current location is centered This will also disable the shadow and the subearth marker until the next Update from the Main window If over a feature the popup will also contain i
183. rth View Zoom OSN Limiting A magnitude Moon with a i i Equatorial standard tag Na l orientation VW A Image Scale 8 20 2001 16 26 12 CDT This is a schematic view of Saturn its rings and moons at the indicated date and time In addition background sky objects may also be displayed The scale at the left controls relative magnification The scale at the right controls the dimmest magnitude which will be displayed Saturn and its rings are always displayed The values range from 20 at the top and 0 at the bottom Objects dimmer than the value specified are not shown Nominal celestial directions are indicated at the top and right edges Moons are displayed only if they are geometrically visible Use the top view to see whether they are also in sun light Version 3 5 2 Page 8 1 Saturn View 8 1 Mouse functions The mouse may be used to identify any object in the Saturn view Position the cursor near the object of interest and select the right mouse button A popup menu will appear with the objects name current location and magnitude 8 2 Control menu Print This selection allows printing the current Jupiter view or saving it to a file Field Stars This selection activates the Field Star setup window For more information about this facility see the Help for the Field Star window itself 13 4 Telescope command This option causes the location of Saturn to be sent to a fifo The intent is for the fifo to
184. ry is searched then auxil off the shared directory Close closes the History window Help displays this information 28 Version 3 5 2 Sky View 10 8 Trails The location of any object on the Sky view may be computed at regular intervals and displayed by setting up a sky trail Use the Sky View Trails Setup dialog to select the interval number of steps formatting details and which steps you would like annotated 815 The trail setup dialog is accessed from the popup which appears when the third mouse button is activated when the cursor is near an object Any number of objects may have trails The trail is created by computing the location of the object at several intervals Each new location will be drawn with a tick mark and connected with a line to its previous location The trails remain correct if the display coordinate system is changed Trails may be turned on or off without loss of trail information Trail information is discarded if a trail is turned off when a new Main menu Update is performed If any point on a trail is selected using the third mouse button the information displayed is as per the object at that time The times displayed next to trailed objects are always in UTC Trail information is not subject to the constraints in the Control gt Filter dialog i e trailed objects are always shown Note that in Alt Az mode if an object goes below the horizon the line segments and tick marks of the trail are displayed but
185. s gt Time zone gt Local Set the time to local midnight Main gt Local Time gt select 00 00 00 shortcut Page 2 20 Version 3 5 2 Main Window commit to the new date and time Main gt Update note NEW CIRCUMSTANCES stops flashing bring up the data table Main gt View gt Data Table if the RisTm and SetTm columns and the Sun row are not visible use the Setup option to enable at these columns and rows bring up the plot control window Main gt Tools gt Plot define a plot with four independent traces with local date on their X axis Plot gt Select fields note how all labels which can be used for plotting now look and operate like buttons as you press them they form the definition of what will be saved for plotting watch the X and Y columns of the Plot window be filled in as you define the variables to plot Main gt Local Date Main gt Dawn Main gt Local Date Data gt Sun RisTm Main gt Local Date Data gt Sun SetTm Main gt Local Date Main gt Dusk Plot gt Select fields turns buttons back to labels When you are finished the lower portion of the Plot window should look like this Tag x Y LD Dawn LD Sun RisTm LD Sun SetTm LD Dusk DOU gt If you make a mistake you must start over Undo is on my list If you wish you may edit the Tags to more accurately denote their meaning such as D R S and d Case is significant but you only get one character Set up Main to generate
186. s case The fifo approach is actually a bit more efficient than the file approach because no polling is required Save as Version 3 5 2 Page 10 19 Sky View The image currently displayed if any may be saved to disk as a FITS file The file name is specified in the text field provided If Auto name is enabled a filename is automatically created derived from the RA and Dec of the center of the image An attempt is made to preserve any existing directory and filename extensions such that the filename is constructed between the right most and the right most characters if possible When an image is saved its current contrast settings are added to the FITS headers If these fields are present when the file is opened these settings will automatically be put back into effect See the Help for Images gt Processing tools for details Open This section is the way to open a local disk file for display Use the File Selection Box at the bottom to choose the desired file Browse your file system using the Directory and File lists then double click on the desired file Or the file name may be typed or pasted into the Selection text field after which you click Open You can browse to any directory on your system for which you have suitable permission of course but there are two convenience buttons on the right that are particularly handy One jumps straight to the system wide Shared XEphem directory and the other jumps to your
187. s in the History list This is handy for saving your favorite views for easy display The top pushbutton in the History pulldown menu brings up this window to Edit the list Additional pushbuttons in the pulldown menu allow any one history entry to be applied immediately The control window shows the current set of History entries one per line Each line has the following format Buttons Page 10 Apply will engage the given entry in the same way as choosing it from the pulldown menu Up and Down allow the entries to be rearranged as desired Remember to Save see below to keep the changes permanently for next time Delete will remove the given entry Replace acts as a combination Delete and Add see below The next section shows the basic display modes the center coordinates and field of view The field on the right allows you to enter a short descriptive label for the entry across the bottom allow for additional control of the History list Add will capture the current Sky View settings and create a new History entry A default label will be created but you should probably change it to something more descriptive if you plan to Save the list Save will write all of the current History entries to a file The file name is xephem_skyhist and will be created in the per user directory Load will read an existing file of History entries that has been previously Saved and make them the current set First the per user directo
188. s to ESO and STScl in general for offering this service at all Thanks to Seiichi Yoshida seiichi muraoka info waseda ac jp for a subtle Page 18 2 Version 3 5 2 Credits fix to the constellation code in 3 1 The sample spacecraft elements were furnished by Ron Baalke baalke jpl nasa gov Thanks to Vance Haemmerle vance toyvax Tucson AZ US for his updated and appended lists of spacecraft elements and work on improvements to the solar system plotting of long period trail sequences Thanks to Jeroen Valkonet jeroenv cvi ns nl for planting the seed which grew into the new bitmap clipmask approach of drawing the stars Thanks to Jim Bell jimbo cuspif tn cornell edu and the team at Mars Watch for encourage support and ideas for the first Mars albedo map in XEphem The map as of Version 3 3 is from http maps jpl nasa gov mars html Thanks to Dimitromanolakis Apostolos lt apdim grecian net gt for his contribution leading to support for fetching DSS in gzipped form Thanks to Miguel Albrecht malbrech serv2 hq eso org at ESO for his assistance and support of their fine Web access facilities to the GSC Rotated trail text uses the xvertext package Here is the copyright xvertext 5 0 Copyright c 1993 Alan Richardson mppa3 uk ac sussex syma Permission to use copy modify and distribute this software and its documentation for any purpose and without fee is hereby granted provided that the above copyright notice appea
189. scroll the list to the next site that contains the search text ignoring case and blanks A new file of site definitions may be installed at any time Type in the name of the file test field then type Enter or click on File to read in the file Or click on Browse and use the File Selection Dialog to locate the desired site file Pressing Ok in the FSB or double clicking on a file name will load the new file and close the FSB window File format XEphem stores sites in the file xephem sit Each line in the file consists of 5 fields each separated by a semicolon as follows Name Latitude Longitude Elevation Timezone where Name is the City State Country or other designation up to 40 characters Latitude is DD MM SS followed by an N or S to indicate north or south of the equator Each portion is separated by a blank Longitude is in DDD MM SS followed by an E or W to indicate east or west of the prime meridian in Greenwich England Each portion is separated by a blank Elevation is in meters If you do not know your elevation put 1 0 Timezone indicates the offset from GMT and savings time information The format matches that of the POSIX standard fully described in the manual page for the tzset 3 function The format is basically summarized as std offset dst offset start time end time Here are a few examples Munich Germany 48 140 Ny 1157 OE 523 MET 1METDST M3 5 0 M10 5 0 New York New York 40 45 6
190. see the help items for these features While looping with Pause set to 0 only the graphical display is updated though numeric information is always updated internally each step If a User Defined object is set elsewhere in XEphem and an unused column is available it will automatically be selected and Center will be activated as a convenience 5 3 View menu Cylindrical Spherical Weather map These radio buttons select from several possible Earth projections Cylindrical Displays the entire Earth surface projected onto a cylinder Primary advantage is the entire surface is visible at once Particularly good for plotting satellite ground tracks Major disadvantage is distortion near the poles Spherical Displays the Earth as it would really appear from space The primary advantage is the sense of reality and lack of distortion Weather map Displays a global montage of satellite cloud imagery ice sea and land temperatures courtesy Space Science and Engineering Center at the University of Wisconsin The image is a gif file retrieved from http www ssec wisc edu data comp latest_cmoll gif It is updated once every six hours All other graphical features of the Earth view remain available as overlays to this image Primary advantage is ease in determining whether weather will effect visibility of a satellite pass If you have trouble accessing the image directly from XEphem the program will also use the file tmp latest_cmoll gif if it
191. separate main from the real ObjX and ObjY and ObjZ The ObjX Y Z ey Paint Sky Wark Tel tots Eabha window always works on these working copies The working copies and the real ObjX Y Z only interact K wets lua Ma Help when using the Ok Apply and Reset control as described shortly Page 13 6 Version 3 5 2 Data This window is always displaying information from one of these working copies as indicated by the small radio box in the top center of the window The radio box may also be used to change whether ObjX Y or Z is being displayed and manipulated We will refer to the one selected as the current working object The radio box in the upper left displays the basic type of the current working object This can be changed by selecting another of the collection of toggle buttons In the left and center of the window is an area that lists each field for the current working object and its present value The list is adjusted to correspond to the fields that are associated with the type of the current working object These fields may be changed by selecting the button that contains their value This will bring up a small text entry window A new entry may be typed into the window box and applied by typing Enter or selecting the Ok button The value may be left unchanged by selecting Cancel Along the right edge of the window is a list of each object currently loaded into the XEphem database See the Help for the Database Load and D
192. so in the Overview window is one little gray rectangle representing each XEphem window that is currently open on the workspace When you first start XEphem only the Main window is up so you see one such rectangle To move this rectangle around on the workspace as well as the real XEphem window which it represents press Shift then click on the rectangle and drag it around The Overview window itself may also be moved in the usual manner by clicking in its title bar and dragging it around Note that it always remains in the same place relative to the screen not the workspace You can learn even more about the Overview window by clicking on the in its upper right corner The workspace and all its XEphem contents appears as one entry on the Windows Taskbar The taskbar will read Microlmages X Server but you can think of it as the XEphem workspace You will not see the individual XEphem windows on the Windows taskbar The entire XEphem workspace may be minimized by clicking on the usual symbol in the upper right corner of the workspace In the upper right of each XEphem window is a small x which will close that window within the MI X workspace When the main XEphem window is closed the entire workspace is also closed To resize a window click on the edge and drag as desired With a bit of practice this is actually all quite useful and expedient Please give it a little time 1 3 2 File Structure In this section we describe the disk file structu
193. strate displaying stars from the Hubble GSC catalog in the sky background This example is taken from Sky and Tel July 1995 page 72 for convenience use UTC for all time displays Main gt Preferences gt Time zone gt UTC set time to 00 00 using shortcut Main gt UTC Time gt 00 00 00 set date to 24 July 1995 using the interactive calendar Main gt Year gt 1996 Main gt Year gt 1995 Main gt Month gt July Main gt 24 Version 3 5 2 Page 2 17 Main Window commit to new date and time Main gt Update note NEW CIRCUMSTANCES stops flashing read in asteroid and NGC databases Main gt Data gt Load Delete in lower right corner double click on asteroids edb or could have single clicked and then pushed Append similarly double click on NGC edb scrolling a bit if necessary Control gt Close select 121 Hermione to be Object X Main gt Data gt Search memory ObjX Y Z in the upper center click on ObjX in the lower right type hermi then Enter in the Search text field this finds 121 Hermione in memory and stages it to become ObjX you may also browse by scrolling through the list at right and selecting the candidate object s button load this into Object X and dismiss the window Ok display asteroid trail on sky view Main gt View gt Sky View Locate gt 121 Hermione set Field of View to about 1 5 degrees using scale on left Control gt Filter set Sol Sys Lim Mag to 16 using scale
194. sx is the standard deviation of the pixel values along a row Y 349 1 Dec 41 32 32 1 A XFWHM 2 p 4 6 Base 36623 sy is the same for a column YEWHM 3 0p 5 1 Peak 39088 A is the peak height of function g xm ym g inf inf Sr Help B is the mean of the row and column pixels mx my is then taken to be the location of the star the volume as proportional to A sx sy as a measure of its magnitude and B a measure of the mean noise level of the surrounding pixels In practice we find this method converges quickly and yields positional results accurate to 2 pixel or so Magnitudes and their error estimates depend strongly on whether the image was ever compressed proper image cleanup nonlinearity of ADU counts with brightness and other Version 3 5 2 Page 10 23 Sky View factors When these factors are properly addressed magnitude ratios seem to be good to 02 mag or so Back to the GUI the text box shows the results of this fitting process on the image pixels that are centered on the cursor and lie within the area defined by the magnifying glass settings whether or not the glass is actually turned on The numbers report the following Relative magnitude difference and error estimate between the current star and the reference star Position of the star in image coordinates and in RA Dec if WCS header fields are present Full width half max of the star in each dimension in pixels and in arc seconds if the im
195. t 1 Day Every 5 Right 1 Week Every 10 Above 1 Month First Last Below 1 Year Mid Last Up 45 Custom H M FAMEL Down 45 peo None Path Left Path Right fonts start Small Whole min Format Medium Whole day H M Large Whole interval Date Huge Now Number of tick marks Ok Apply Close Help This window allows you to define a set of time values spaced at regular intervals beginning at the current XEphem time and define which and in what manner values will be annotated with a time stamp This is a general purpose facility used in several places throughout XEphem generally for the purpose of establishing a trail of object motion This description will be of a general nature For the specific information on how a given XEphem view uses these time values please refer to the Help information associated with that view Seven parameters must be specified Orientation This choice determines Where the stamps appear in relation to their corresponding tick mark The radio box in the upper left corner provides several strategies for placing the time stamps near each tick mark The first several options should be obvious The last two Path left and Path right cause the time stamps to be placed to the left or right side of the trail path as one would perceive these directions when traversed in forward order In no case are the time stamps ever drawn to require you to turn your head more than 90 degrees left or right Interval This is t
196. t 13 3 File naming 1 9 Filter 10 7 10 12 Find close pairs 12 7 FITS 10 1 fixed 13 3 Fixed 13 8 Fixed objects parameters 13 8 fleur 5 2 10 4 focallength 10 16 Font 15 2 Fonts 2 11 Format 15 2 Forward1 2 4 FOV 10 29 Full Moon 2 4 function 12 4 g k magnitude 13 9 galactic 3 3 Galactic 10 10 Galilean 7 1 gamma 4 3 Gamma 10 21 Gaussian 10 23 Geocentric 2 7 3 4 Germany 2 20 Getsky 12 13 ghostscript 1 9 Glance 12 9 GMT 2 14 goal 12 5 GoTo 10 5 10 26 gray 4 1 Grid 10 9 Groombridge 13 14 GRS 7 1 GSC 2 17 13 12 H G magnitude 13 9 HA 3 2 Hardie 3 2 heliocentric 3 3 heliocentric latitude 11 4 heliocentric longitude 11 4 help tips 2 7 Hipparcos 13 14 History 10 28 Page l 2 HOME 12 2 Horizon 10 7 10 11 10 14 Horizon file format 10 14 hour angle 3 2 Hubble 13 12 hyperbolic 13 4 Hyperbolic 13 10 Image Tools 10 20 images 2 19 inclination 13 4 13 8 13 10 13 11 Interval 15 1 JD 2 6 JPL 12 1 Julian 2 2 Jump to Max 10 22 Jupiter view 7 1 Just dots 10 9 Keyspan 1 10 Label 15 2 Latitude 2 1 Legs 11 3 libration 4 1 license 1 6 light 3 3 light curves 12 10 Limb 3 3 4 4 List 12 3 List values 12 3 Live dragging 10 11 Log Bell 2 7 Longitude 2 2 longitude of ascending node 13 8 looping 1 11 LST 3 2 LST O 2 3 luminosity 13 9 Lunar 2 25 LX200 1 10 Magnifying glass 10 4 Magnifying Glass 10 22 Magnitude 10 10 magnitude 10 10 10 24 Main Window 2 1 Major resources 2
197. t Moon and Planet phases and orientation in Sky View add sidereal day and month trail intervals just label month and year tickmarks in trails when they change comet tail pointer meteor showers dedalus Iridium flares allow using a tracked object as the reference for a trail arbitrary solar system perspective option for rise set info to be Today or Next add Plot JD as years to plot display add H M S trails Format option way to keep list close pairs while looping way to keep skyview listing ongoing while looping add general text and graphics annotation for all views with save use better earth shape model at least an oblate spheroid Version 3 5 2 Page 17 1 Notes add separate Sol view with real time Net sunspot and coord grids add T gt F and F gt T to Binary min max to Extreme and stop when T F or lt 0 gt 0 Jupiter satellite shadows use user defined horizon for rise set calculations some means to automatically print while looping PS multi page format interactive way to create user defined horizon with labeling way to repeat the Solver for more solutions as in solver in a loop support Sloan and GSCII when complete change to an XML database format then add real doubles variables etc set an ROI in sky view and click an object to ask when will it be in box more hot keys more flexible time stepping Known Bugs Pref gt Zone should apply everyw
198. t fields toggle button to make each field in the other windows that are eligible for listing appear as a pushbutton Select each such button as desired to form each column of the listing As you make the selections they are listed in the table Once all the column choices have been made you may return all the windows to their normal operational appearance by reselecting the same toggle button Specifying the listing file Type the name of the file to be used to contain the listing in the text field provided When XEphem first needs to write to the file it will first check for the existence of the file and if it exists ask whether you wish to append to the file or overwrite it A leading in the filename will get expanded to the value of your HOME environment variable You may also elect to print the file in LaTeX table format by pressing the given button before beginning to list to the file Choosing to include column headings When this option is selected column headings are written to the output file each time the file is opened Specifying a listing file title All lines within a listing file that do not begin with an alphanumeric character are considered comments and are ignored When XEphem first writes to a listing file it will place the contents of the title text area if it is not empty into the file as a comment for your convenience Generating the listing entries Version 3 5 2 Page 12 3 Tools Once the fields
199. t is closed However for convenience if any of the fields in the More Info window are being used for listing plotting or solving the continue to be updated even when the window is closed 4 3 Views menu Spacecraft If set and the Scale is at 6 then all spacecraft landing sites are marked and labeled on the image Ifthe Scale is less than 6 then only the Apollo sites are marked Features This sets whether additional non spacecraft Lunar features are labeled on the image More features are labeled at larger scales Even at the largest scale all of the features are not labeled However all features are searched at all scales when using the right mouse click to interrogate a location Sky background This sets whether to show objects within the current field of view that are in the XEphem database memory or available from the Field Star facility The size and symbol used for the object matches that of the Sky view when set for a minimum magnitude of 12 While this option is on XEphem will continue to retrieve field stars as required Use real image This sets whether to render the Moon using a real image or just a simple schematic drawing of the sun lit and earth lit portions The latter option is primarily just for simpler printing Even while this option is on the magnifying glass will still show the real image and the lunar features database is still accessible via the right mouse button Pen Umbra This sets whether to show
200. t positions were implemented for XEphem by Michael Sternberg lt sternberg physik tu chemnitz de gt based on the papers Planetary Theories in rectangular and spherical variables VSOP87 solution by Bretagnon P Francou G in Astron Astrophys 202 309 1988 ftp ftp bdl fr pub ephem planets vsop87 and Representation of planetary ephemerides by frequency analysis Application to the five outer planets by Chapront J Astron Astrophys Suppl Ser 109 181 1995 ftp adc gsfc nasa gov A pub adc archives journal_tables A AS 109 181 See the comments in chap25 h and vsop87 h for accuracy estimates The high precision Moon code was also implemented for XEphem by Mr Sternberg based on code supplied by Stephen L Moshier lt moshier world std com gt at ftp ftp std com pub astronomy selenog zip Mr Sternberg also incorporated the algorithm for deltaT based on code also provided by Mr Moshier See the comments in deltat c for full references My greatest thanks to Messrs Sternberg and Moshier for their generous and kind assistance in making XEphem a program of first class accuracy The improved lunar libration trig series fit to JPL DE403 was provided by Stephen L Moshier lt moshier world std com gt Many thanks to Michael Naumann Michael Naumann eso org and Miguel Albrecht malbrech eso org at ESO and Tim Kimball archive stsci edu at STScl for their help and support accessing the DSS at their institutions And thank
201. tegory heading otherwise if at least one Minor resource is out of date a hollow bullet is used Whether or not any resource is in fact Saved may always be independently set as desired using its toggle The discussion above refers only to whether the toggle for each resource is set automatically after each Refresh A key is provided at the top to remind you to what the two styles of bullets refer along with a count of the total resources that are out of date in each class Note that the information in this window does NOT automatically track changes in resources as XEphem is used You must use Refresh see below to update the status here when desired In particular the values which are Saved are what they were the last time Refresh was performed not what they actually are at the moment Save is activated If the Autosave option is both on located in the upper left all Major resources that are out of date and selected when XEphem is Quit will automatically be Saved without first being asked to confirm using this window The controls along the bottom behave as follows Save Each resource with its toggle button depressed is written to the per user resource file named at the top If the file already exists it will first be copied to XEphem bak in the same directory If a resource already exists in the file it will be edited in place otherwise a new entry is added at the bottom Other lines in the file are left unchanged After using Save all res
202. the orientation on the selected location 5 2 Control menu Print This selection allows printing the current Earth view or saving it as a Postscript file Objects This brings up a window to control which of the User Defined Objects OBJX Y Z are displayed See its own Help for full details Set Main This sets the Latitude and Longitude of the Main window to that of the current position of the Earth view This also causes all other information and views to be updated to reflect the new location Page 5 2 Version 3 5 2 Earth View Set From Main This sets the Earth view position to that of the Main window Movie Demo This sets up an automatic display movie of the Earth This is done by setting the N Steps entry in the Main window to a large value setting the Step to 5 minutes and starting XEphem looping The movie can be stopped by selecting this option again or by selecting Stop from the Main window Close This causes both the Earth view and the extra statistics window to be closed 5 2 1 Objects dialog This window allows you to display up to three objects on the Earth view simultaneously with optional ground tracks There are three columns one for each object Click on an Option menu then slide and release over the desired object The list will always contain the major Planets Sun and Moon as well as the three User Defined Objects known as ObiX Y Z if they are defined see Main gt Data gt ObjXYZ
203. the top control the view additional information and the ability to overlay the ground positions of up to three objects The scales along the bottom and right edges display and may be used to control the center location Any of basic Planets Sun and Moon as well as ObjX Y or Z from the XEphem database may be displayed on the map The surface location of an object is marked with a bulls eye The concentric circles indicate the locus of points at which the object appears aI to be 0 30 and 60 degrees above the local horizon When the Earth view is first displayed the Objx Y Z objects will automatically be preselected and the view centered on ObjX if they are defined After that you are free to change things as desired Note that these can be preset directly at startup by using edb database files containing exactly one object each see Data gt Load gt Help gt on Control for more information 13 1 10 14 2001 2 53 53 CDT The location defined in the Main window is marked on the map with a plus If a solar eclipse is occurring on the Earth a small X will mark the location of central totality Try July 11 1991 around 18 00 UT or May 10 1994 around 16 00 UT All computations for Earth satellites are based on the NORAD SGP4 SDP4 code This code produces the exact same output as their test collection This means however that it is not Version 3 5 2 Page 5 1 Earth View integrated particularly tightly with the r
204. this manner is currently restricted to 30 arcminutes Once an image is displayed by either method all Sky View features are available So you may add a grid overlay load and display field stars track the coordinates with the cursor etc etc as with any Sky View Investigate the various Controls from the menubar of the Sky View to see what all is available For example if your image has WCS or DSS coordinates to display field stars over the image Set up a source for the field stars if not already set up Sky View gt Control gt Field Stars follow the directions in the Help Turn on the following options if not already on Sky View gt Options Auto mag Field Stars Next explore the image processing capabilities Sky View gt Images gt Processing tools The image will remain in the Sky View until the direction is changed If you loaded a DSS image you may want to save it to your local disk for easier access next time 2 7 5 Sunrise plot In this example we will plot the times of local dawn sunrise sunset and dusk over the course of 2001 Set the date to Jan 1 2001 Main gt Local Date gt 1 1 2001 you might have to enter this differently depending on your current Date Formats preference you could also set the date by using the interactive calendar at the right select the current month slide and release over January then push the 1 date on the calendar Show times in local timezone Main gt Preference
205. thmetic functions Here is the complete list amp amp gt gt l lt lt abs floor sin cos tan asin acos atan degrad raddeg pi log logl0 exp sqrt pow atan2 The function is entered into the text line provided It may utilize most of the fields from the other XEphem windows Press the Enable field buttons button to make each available field a button Where ever a field is desired in the function position the text insertion cursor at the desired position and select the field its name will be inserted into the function text When you are finished defining the function turn off the field button appearance by selecting the Enable button again Once you get to know the names of the fields you may also enter them manually if you prefer Compiling the function Once the function has been entered as desired it must be compiled by selecting the Compile button or by pressing the Return or Enter key on your keyboard If there are any errors a diagnostic message will appear just below the function Once a function has been successfully compiled the message will read No compile errors If the function is modified a message will remind you that it has not been compiled Each time a function is successfully compiled XEphem updates all fields and evaluates the function As Page 12 4 Version 3 5 2 Tools explained below this can be used as a sort of astronomical calculator even when not actually solving anything S
206. through the sky This motion is called libration A dot is placed on the circumference of the image to indicate the limb position that is currently tilted most towards Earth due to libration The angular position of the dot is placed accurately but the image rendering is not adjusted for libration effects Thus the surface features over which the dot and the terminator appear in the image are only approximate See the Help for More info under View for more information on libration 4 1 Mouse functions Left button Activating the left mouse button while over the lunar image will display a small magnified 2x view of the lunar surface under the cursor The magnified image will track the cursor as it is moved around the image The latitude longitude and solar altitude of the location are displayed in the More info window See Help for View for more information about this window Version 3 5 2 Page 4 1 Moon View Right button Activating the right mouse button while over the lunar image will bring up a popup menu If the location is near an item in the lunar features database the name of the feature its type diameter in miles or km depending on Preferences gt Units location and solar altitude at its center are displayed in the window A toggle button will also be present which controls whether the label for the feature will be persistent that is shown regardless of whether View gt Features is activated Persistency is automat
207. ti subsolar point is at 90 The libration in longitude is positive towards lunar east latitude is positive towards lunar north The Limb angle is zero at lunar north and increases towards lunar west The Tilt is the number of degrees the Moon is tilted towards Earth around an axis defined by the librations in latitude and longitude The limb location that is titled most towards Earth is indicated on the image by a small dot Any of the values in the lower portion may be used for plotting listing and solving in the usual way as described in the Help entries for these Control options The values are always current when used in this way even if the main Moon view is closed For faster looping close the main Moon display to prevent it from being redrawn each time Page 4 4 Version 3 5 2 Moon View 4 4 Scale menu This pulldown menu presents a list of factors by which the lunar image may be scaled The image is presented in a scrolled window for panning if it is larger than the overall window Version 3 5 2 Page 4 5 Moon View Page 4 6 Version 3 5 2 Earth View 5 Earth view Up to 3 simultaneous Sites Altitude loci for Terminator ground tracks database Horizon 30 60 N N Control Vie Help 10 14 2001 2 53 53 CDT Control View Help This view displays a schematic of the Earth with continent outlines The projection may be spherical or Mission Control style The controls available from the menu bar across
208. tion is the amount of color purity where lower values mix in more white Value is like brightness where 0 is totally black The text field at lower left allows you to type a color using one of the standard descriptive names such as steel blue or in hex RGB notation for example ff0000 for pure red 00ff00 for pure green 0000ff for pure blue After typing the desired value press Enter to set the scales and see the color in the patch This field is also set automatically when the scales are used to set a color during Grabbing see next and when a color context is retrieved In the Control menu is a toggle button for Night vision This changes the XEphem background to black and uses the Night vision color for all text Clicking this back off will restore the previous colors Note that when Night vision is on you may not change the colors it effects This is to eliminate confusion with regards to wheter or not they are new in the Save window In the Control menu is a button labeled Grab It may be used to capture any color on the screen Press this button and the cursor will change to a crosshair Move the cursor around on the screen and the color of the pixel under the crosshair will be displayed press Button1 to capture the color and resume normal cursor operation The history list in the lower left stores each color name that is used from the name field making it easier to reuse a color Selecting a name will copy it to the name field
209. top the movie Close This removes the Jupiter display and the additional information window if present from the screen 7 3 View menu Top view Selects whether to display another window located over the pole that is on top in the front view This window will try to remain aligned above the main view when either is resized Moons are displayed only if they are in sun light Sky background Selects whether to also show objects within the current field of view that are in the XEphem database memory or available from the Field Star facility The size of the object is determined by the limiting magnitude as specified by the scale at the right Objects are drawn using the same symbols as used by the Sky view While this option is on XEphem will continue to retrieve field stars as required Bright moons Page 7 2 Version 3 5 2 Jupiter View If this option is in effect then the diameter of all moons will be increased by 3 pixels This option also insures that even those moons which are dimmer than the limiting magnitude as specified by the scale to the right will be drawn with a circle of diameter 3 pixels Tags Search whether to show the Roman numeral designation beneath each moon and a 1 arc minute scale calibration line Flip T B Flip L R These allow the scene to be flipped vertically and horizontally respectively 7 3 1 More info dialog Central Meridian Longitudes degs Sys I 48 314 GRS Sys II Long 6
210. trol gt Options gt RA Dec is set You may click on any of the tick marks with mouse button 3 to get the circumstances of the asteroid at the various times along the trail You can change the trail parameters by using Change Trail and proceeding as before With luck you ll have a pretty appulse to watch 2 7 2 Solar eclipse path This example displays the location of totality on the Earth for the solar eclipse of July 11 1991 for convenience use UTC for all time displays Main gt Preferences gt Time zone gt UTC set time to 17 25 00 Main gt UTC Time enter 17 25 00 then Ok or just Enter note you may use almost any punctuation character instead of and you need not give leading zeros for example 17 25 0 set date to 11 July 1991 Main gt UTC Date enter 7 11 1991 note this should be entered according to the current date format preference for example after Main gt Preferences gt Date formats gt Y M D you would enter the same date as 1991 7 11 commit to new date and time Main gt Update note NEW CIRCUMSTANCES stops flashing display the Earth Main gt View gt Earth A black cross should appear a little southwest of Hawaii That is the current center of totality display the subearth point of the Moon i e the point on the Earth s surface at which the Moon is directly over head Page 2 16 Version 3 5 2 Main Window Set Moon as current object Control gt Objects Click on Disp
211. ts name Version 3 5 2 Page 6 1 Mars View type diameter or largest dimension and location If not over a feature the cursor location is shown 6 2 Control menu Print This selection allows printing the current Mars view or saving it as a Postscript file 14 Close This selection will remove the Mars view from the screen If it is open it will also remove the More Info window 6 3 View menu Flip T B This sets whether the image is flipped top to bottom Flip L R This sets whether the image is flipped left to right Grid This sets whether a coordinate grid is drawn over the image Each line is spaced at an interval of 15 degrees Also unless the image has been repositioned by hand an X marks the center of the image that is the subearth location Features 4 Landing site 11 Catena catenae Chain of craters 2 Cavus cavi Hollows irregular steep sided depressions 14 Chaos Distinctive area of broken terrain 14 Chasma chasmata A deep elongated steep sided depression 11 Colles Small hills or knobs 132 Crater craters A circular depression 1 Dorsum dorsa Ridge 52 Fossa fossae Long narrow shallow depression 4 Labes labes Landslide 2 Labyrinthus Complex of intersecting valleys 15 Mensa mensae A flat topped prominence with cliff like 1 Mons montes Mountain 10 Patera paterae An irregular crater or a complex one with 18 Planum Plateau or h
212. tude and Step are entered and displayed in d m s format and also fall into the general triad format The same rules apply to these with respect to only having to set the portions that are being changed and the typing conveniences For typing convenience the slash and colon used in any field may also be entered as a hyphen semicolon or comma Yes 1 1 1 works for 1 BC Page 1 12 Version 3 5 2 2 Main Window Load local net Help in every Ze Investigative 9 ways to re search Choose fonts view data define objects colors formats i save Networking updates N quit En Local circumstances Date and Time File View Tools Data Preferences Make changes then press Update to run Local CDT Calendar Chicago Illinois October 2001 Latitude 41 52 28 Su Mo Tu We Th Fr Sa Longitude 87 38 22 2 5 3 18 en nn z 14 15 NM 17 18 19 20 21 22 23 24 25 26 2 Atm Pres 1010 mB 28 29 30 31 FMI Equinox 2000 0 5f 8 9 10 lt lt lt Now gt gt gt Time DO Night Tulian 2452196 34661 Sun Dip 18 UTC Date 10 13 2001 Dawn 5 28 UTC Time 20 19 07 Dusk 19 44 Sidereal 15 58 23 Length 9 44 TZ Name CDT LST O 0 40 41 TZ Offset 5 00 00 444 Looping Now Local Date 10 13 2001 Step RT Clock Local Time 15 19 07 N Steps 1 Delta T Auto 64 94 Pause 0 Update window Calendar and time shortcuts Sun moon Dusk Dawn
213. u Also provided is a scale by which you may set the size of your local seeing disk The image will be blurred to roughly simulate the resolution under those conditions The computing time will increase with larger seeing values For browsing purposes the values may be changed as desired Adjust any or all scales then press Apply to put the changes into effect Forcing changes in this way will also temporarily disable the shadow At the time of the next Update the correct current values and the shadow will be reinstated The Apply button is made insensitive if the scale values are correct for the current time the button becomes sensitive only when the scales have been moved manually The values in the lower portion may be used for plotting listing and solving in the usual way as described in the Help entries for these Control options from the Main window The values are always current when used in this way even if the main Mars view is closed For faster looping close the main Mars display to prevent it from being redrawn each time 6 3 2 Moon info dialog Version 3 5 2 Page 6 3 Mars View Control View Help 11 14 2000 7 56 07 UTC This is a schematic view of Mars and its moons at the indicated date and time In addition background sky objects may also be displayed The scale at the left controls relative magnification The scale at the right controls the dimmest magnitude which will be displayed Mars is always displayed T
214. ues if an Update is performed The Equinox for the RA and Dec values is the one shown in the Main window The controls across the bottom perform as follows Close Closes this window Sky point Marks the coordinates shown on the Sky View map recentering if necessary to place it in the field of view Page 12 12 Version 3 5 2 Tools Get sky Loads each field from the current center position of the Sky View Canonize Reformats each field in a consistent manner for easier viewing Help Display this text Version 3 5 2 Page 12 13 Data 13 Data XEphem works with objects in memory The controls in this section provide facilities to manage this set 13 1 Load and Delete control Help 18653 Loaded Objects 1683 Solar elliptical 0 Solar hyperbolic 0 Solar parabolic 0 Earth satellites 1760 Clusters C U 0 6893 Galaxies G H A 873 Planetary Nebulae P 300 Nebulae N F K Pulsars L Quasars Q Radio sources J 11 Supernova Remnants CR 6998 Stars S V D B M T 130 Undefined 6 Loaded Catalogs Delete 3485 AAVSO edb Delete 110 Messier edb Delete 8300 NGC edb Delete 1934 SAC edb Delete 3141 YBS edb Delete 1683 asteroids edb omo Filter usr local telescope xephem catalogs edb Directories Files e xephem catalogs SAC edb e xephem catalogs UGC edb be xephem catalogs gsc WashDouble edb e xephem catalogs usno YBS edb asteroids edb asteroids_dim edb bs edb egcg edb Se
215. urces you wish to use The window is accessible from the Main window as well as from the Control menus of most graphical views XEphem uses the term field star to refer to the huge numbers of faint stars visible in any real world view of the sky Field stars are generally far more numerous than could be reasonably accommodated in the XEphem edb database format For this reason they are stored and made available in their own special compact forms for utmost efficiency The downside to this approach is that field stars are not included in the totals presented by the Data gt Load window nor are they available for searching or inspection using the Data gt Search window This results in little loss of generality however since once found they may be assigned to the user defined objects ObjX Y or Z by using the popup menu in the Sky view and thus be further investigated via the Data table window 3 The controls in the Field Stars setup window are grouped into categories depending on the basic source of the stars Hubble Guide Star Catalog This is the seminal work created by the Space Telescope Science Institute to support the Hubble Space telescope It contains from 13 million unique stars or about 300 stars per square degree of sky It may be accessed with XEphem in the following ways ASP CDROM Directory This choice enables reading field stars from the Hubble Guide Star Catalog available on two CDROMs published by the Astronomi
216. use over the ISS press the right mouse button slide down and release over Create trail select Interval Custom and type in one minute as 0 01 also set these options for starters Orientation Up Format H M Font Small Label Every 2 Start Whole interval slide Number of tick marks to about 10 click Apply Version 3 5 2 Page 2 27 Main Window 10 13 2001 15 19 07 CDT Page 2 28 Version 3 5 2 Data Table 3 Data Table Control Help Cns Az Alt Zenith VMag Elong RisTm TrnTm Trn lt SetTm Sun Lib 57 54 29 54 28 28 144 28 28 27 0 0 12 55 17 51 29 37 22 47 Moon Tau 170 52 24 68 54 39 21 05 21 13 147 3 1 26 8 11 69 08 15 54 Mercury Vir 68 28 47 36 36 12 126 36 12 1 6 19 3 11 13 16 38 37 36 22 03 Venus Sgr 328 47 4 71 24 19 161 24 19 4 1 33 3 163142099 2233 120 Mars Vir 80 40 08 12 10 19 102 10 19 1 7 46 0 8 59 14 56 46 41 20 54 Tupiter Tau 214 46 4 65 24 04 24 35 56 2 8 164 2 23 31 6 57 68 45 14 19 Saturn Tau 228 26 40 57 33 22 32 26 38 0 5 173 9 23 05 6 1 65 28 13 25 Uranus Cap 278 36 54 34 05 05 124 05 05 5 8 84 8 18 47 23 48 31 40 4 49 Neptune Cap 286 46 22 45 31 42 135 31 42 7 9 71 8 18 04 22 55 29 00 3 45 Pluto Oph 17 41 28 58 55 34 148 55 34 13 9 22 2 13925949217 36 07 0736 ISS ZARYA Men 184 14 56 29 52 37 119 52 37 9 43 9 46 3 12 9 49 Limb 11 14 2000 7 56 07 UTC This is a table of information about each planet the Sun Moon and any three user defined objects ObjX Y and Z
217. ve it a title Plot gt File name rings plt Plot gt Title Saturn Earth Ring Tilt for 1995 Enable plot file capture Plot gt Create plot file Accumulate 180 steps each 2 days Main gt N Steps enter 180 then Enter Main gt Step enter 2d then Enter Main gt Update runs through 180 steps rather subdued it Version 3 5 2 Page 2 23 Main Window runs faster if you close the Saturn view Display plot file Plot gt Show plot file Plot file gt View gt Show X Axis as Dates Control View B Saturn Earth Ring Tile for 1995 HA 6 5 1 Y za 1 1701 1995 7 01 1995 1 01 1996 There are evidently two crossings i e where the tilt angle is 0 one in late May and one in early August Lets solve for the one in August Main gt December gt August Main gt Update to engage NEW CIRCUMSTANCES Open the Solve control window set up to solve for when the Earth ring tilt goes to zero Main gt Tools gt Solve Solve gt Enable field buttons turn on Saturn info gt From Earth Solve gt Enable field buttons turn off Solve gt Compile Solve gt Find 0 Solve gt Solving is Active Solver is Active Function Clear Saturn ETilt No compile errors Enable field buttons Compile Goal Find Extreme Find 0 Binary Desired accuracy 0 02 00 Current value 2 41637e 06 Close Help Page 2 24 Version 3 5 2 Main Window And go Main gt
218. verages out to more than 10 stars per square degree The set includes the original North and South editions plus the extended supplement The set includes more than 99 of the stars in the original SAO catalog and some 70 of the Henry Draper Catalogue HD While the SAO catalog is more or less complete to V 9 with stars as faint as V 10 the PPM catalog is fairly complete to V 9 5 and goes somewhat deeper than V 10 Hipparcos and Tycho 2 This catalog is a combination of the Hipparcos and the Tycho 2 astrometric catalogs published by the European Space Agency These are now considered the best proper motion catalog in available This catalog contains all Hipparcos stars for which astrometric and magnitude values are assigned and all additional non redundant entries from the Tycho 2 catalog except multiple component entries There is a total of some 2 5 million stars or about 60 stars per square degree One example of a star with high proper motion is Groombridge 1830 HD 103095 in Ursa Major near 11h53m 37d44m For a nice discussion see Burnham s Celestial Handbook Volume Ill page 1978 By comparing its position in either PM catalog with the same entry from the GSC one can deduce this particular GSC field was evidently taken in early 1983 Skip likely duplicates All of the above may be used together with the regular database facility of XEphem If this option is on XEphem eliminates what appears to be redundant entries for the s
219. vertical scale on the right controls the heliocentric latitude your angle above the ecliptic plane Changes to the scales take effect as you drag unless the View gt All Objects option is on in which case the change does not take effect until you release the scale Page 11 4 Version 3 5 2 Tools 12 Tools As interesting and entertaining as the visual displays are in XEphem perhaps its greatest value is its quantitative features The algorithms used for the planets are directly traceable to the JPL DE200 numerical integration and will match the Astronomical Almanac to full displayed precision The natural satellites models were supplied by the French Bureau of Longitudes and are accurate to 0 5 arcsecond between the years 1996 and 2020 2Q98 Topocentric apparent place is computed by starting with astrometric mean place including Solar deflection and applying corrections for precession nutation aberration relativistic deflection parallax and refraction the latter two depend on accurate values for latitude longitude elevation and atmospheric pressure and temperature Comet and asteroid ephemerides do not include perturbations but timely orbital elements are readily available for downloading via the Internet All of this accuracy can be tapped directly as described in the next several sections Many of these features take advantage of one common trait all data fields throughout XEphem may be turned into Pushbuttons which allow the
220. wo forms 1 month day year where day may contain a fractional portion examples 1 1 1993 and 1 1 234 1993 NOTE the format of dates in database files is always M D Y regardless of the current XEphem Date format Preference setting 2 year as a real number such as 1993 123 Field Definitions The first two fields are always Name and Type Remaining fields depend on Type The Name field is the object s name Any number of characters may be present but only the first 13 are retained as significant The Type field consists of a single letter designating the form of the object s motion and must be one from the following set f fixed no proper motion e heliocentric elliptical orbit h heliocentric hyperbolic orbit p heliocentric parabolic orbit E geocentric elliptical orbit i e Earth satellite If Type is f fixed an object class code may follow in the next subfield A Cluster of galaxies B Star binary C Cluster globular D Star double F Nebula diffuse G Galaxy spiral H Galaxy spherical J Radio K Nebula dark L Pulsar M Star multiple N Nebula bright O Cluster open P Nebula planetary Q Quasar R Supernova remnant S Star T Stellar object Version 3 5 2 Page 13 3 Data U Cluster with nebulosity V Star variable if class is one of T B D S or V the spectral class and possibly the numerical subclass designation may follow as 1 or 2 characters in the next subfield
221. xist the file is written as soon as you select Ok If the file already exists you are first asked whether you wish to append to the file or overwrite existing contents The format of the file begins with a header line that captures the conditions in effect when the set of close objects was built Following the header there is one line per pair with exactly the same information as appears in the window list Close This closes the Close Objects window The list is not modified in any way while it is closed 12 4 2 Options menu Auto update When this option is active a scan for close objects is performed automatically each time an Update is commanded from the Main window The prior list is discarded each time The list is never updated when the window is not open Auto list When this option is active the results of each scan are automatically appended to the file specified in the List to file window This works whether the scan was performed explicitly via the Control gt Update command here or implicitly via an Update from the Main window and the Auto update option is active Omit fixed pairs When this option is active then pairs of Fixed objects are not listed Page 12 8 Version 3 5 2 Tools 12 5 Night at a Glance Dusk Now Set Dawn Rise Control Multiple appearances Local timeline ua UTC _M timeline a 8 21 2001 23 26 12 CDT Local date Local date today tomorrow This window displays the curr
222. y dragging the red arrows at the top of the diagram You may control gamma by sliding the scale ust above the graph When XEphem saves an image it adds three fields to the FITS header to save the current contrast settings When it loads an image if these fields are present they are used to restore the same display contrast If these fields are not present the Wide setting is used These fields are XELOGLUT the pixel value assigned to black Version 3 5 2 Page 10 21 Sky View XEHIGLUT the pixel value assigned to white XEGAMMA the value of Gamma 10 4 2 2 Cross Section Slice Opening this section lets you use the mouse to drag a line across the image and display the pixels along that line The graph is labeled vertically in pixel value horizontally as pixel distance from the starting point The line begins where the left mouse button is Help first depressed CO This section may also be opened using the button in the right Sky View toolbar that looks like a slice of bread 10 4 2 3 Magnifying Glass Abell426 fts 530W x 530H Max 47620 ars 395 03 Min 35559 Mean 36792 1 Median 36498 StDev 1179 2 Help Brightness and Contrast Help U Cross section Slice Help Magnifying Glass Size 16 32 Y 64128 Mag 1 2x 4x 8x 23W x 23H Center 46847 280 4 367 3 Max 47139 278 0 367 0 Min 36322 Mean 38422 0 Median 37383 StDev 2477 2 Plot center Row Column Help Region of Interest Help 1 2D Gaussi

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