Horizons Tips For Spitzer Solar System Observers
Contents
1. 2 The specific values shown below are for exampl purposes and should be changed to reflect your specific case 3 Only one TYPE block should be specified per request The others can be deleted or commented out Horizons Tips for Spitzer Solar System Observers with the symbol If they aren t the last model specified will be used TYPE 1 Polygon of four vertices Specify EME2000 RA amp DEC of each of 4 vertices in uniformly clockwise CW or counter clockwise CCW l L Order RA 1 333 946666666 DEC 1 4 80830555 l IEA 2 334 946666666 IDEO 2 4 80830555 l IRA 3 334 946666666 DEC 3 5 8083055 l IRA 4 333 946666666 DEC 4 5 8083055 rn rpm rn rpm m rn rr rr m rn o TYPE 2 Circle Specify RA amp DEC EME2000 of the field center RADIUS UNITS ARCSECONDS W225 TAT ed DEC aha EE 29 94 RADIUS 1800 0 Specify RA amp DEC EME2000 of the field center RAW Right Ascension width UNITS ARSECONDS DCW Declination width UNITS ARCSECONDS PHI CCW rotation angle UNITS DEGREES IEA 22 17 47 20 DEC 05 18 29 9 RAW 3600 DCW 3600 PHI 0 0 SPKID sets the ID number of the body center from which field was obser2. START TIME 2001 DEC 2 00 00 Start of table UTC default STOP TIME 2003 DEC 2 00 00 End of table STEP SIZE IL day Table step size QUANTITIES 2 6 12 14 23 Compute these quantities see doc ANG FORMAT DEG Format of RA DEC HMS or DEG EXTRA PREC YES Additional output digits of RA DEC CSV_FORMAT INO Set comma separated value tabl SSEOF Horizons Tips for Spitzer Solar System Observers Horizons Tips for Spitzer Solar System Observers Appendix 2 Saving Personalized Program Settings The following description of how to save your personalized program settings so that you can for example save observer table parameters and preferences in one Horizons session and then recall and use them in other Horizons sessions is excerpted from the Horizons web page systems news maintained by Jon Giorgini Personalized program settings saved betw Once you have gone return to the main Horizons gt prompt Type SAVE NAME Next time you telnet to Horizons Your out The idea is to save time n sessions through the prompts and defined the output where name contains 1 12 characters type LOAD NAME tput preferences will then be loaded in as new defaults you need not customize your output anew Others in your organization same pre defined format settings by name each time you return to the system can use th DELETE a macro
3. 4 0 03081 SE Horizons Tips for Spitzer Solar System Observers After a few minutes the tool FOV ISPY e mails the following file to the submitter s e mail address Asteroid Comet Search Results JPL Horizons FOV ISPY V1 0 Thu Apr 29 13 07 45 2004 Pacific Trajectory sst spk 030825 040412 091231 SPKID 79 Observation time UTC 2004 Jan 21 13 20 00 000 FOV specification type Rectangle corners Corner 1 RA DEC EME2000 12 02 52 20 00 52 31 8 DEG 180 71752 0 87549 Corner 2 RA DEC EME2000 12 02 10 04 00 48 13 6 DEG 180 54184 0 80378 Corner 3 RA DEC EME2000 12 03 41 10 00 01 59 2 DEG 180 92125 0 03310 Corner 4 RA DEC EME2000 12 04 21 20 00 01 50 9 DEG 181 08833 0 03081 FOV centroid RA DEC EME2000 12 03 15 70 00 25 24 5 DEG 180 81543 0 42347 FOV area arcmin 610 30 Number of objects found 10 Number of objects checked 185676 RA DEC dRA cosD d DEC dt Cnt Dst PsAng Data Arc Error Ellipse Number Name HH MM SS ff DG MN SC f Amag Ar whe arcsec DEG span day Nobs SMAA _3sig SMIA_3sig Theta 7987 1981 EV22 12 02 32 35 00 47 42 9 19 4 ERO 1 53 1488 0 205 9 1981 2002 142 27168 1999 AN21 2 02 24 10 00 48 23 5 19 2 8 44 1 90 1581 4 209 3 1997 2001 64 27293 2000 AX136 2 03 49 08 00 12 35 7 17 3 T023 10 06 917 5 33 1 1986 200 139 53273 1999 F224 2 03 06 07 00 30 35 4 19 2 7 74 4 33 342 8 204 9 1999 2003 132 2001 QY160 2 04 07 10 00 02 04 8 20 1 7 24 2 32 15
4. 7 7 2 the Catalog File Overlay ISPY Input Commands Detail A detailed description of the input commands for ISPY including the three field specification geometries supported polygon circle and rectangle is given below The current configuration of this file would request asteroid positions returned for a circular field of radius 1800 arcseconds centered at RA 22 17 47 20 Dec 5 18 29 9 VLO Horizons FOV ISPY Execution Control VARLIST Apr 15 2004 ftp ssd jpl nasa gov pub ssd ispy mail example long The latest version of this command file may always be retrieved from the above anonymous FTP site The Horizons ISPY program examines a field of view FOV specified in one of three ways listing known asteroids or comets present in the field along with their predicted positions apparent magnitudes plane of sky uncertainties and other relevant parameters In this file 1 Lines must be a variable assignment blank or start with a symbol 2 denotes a comment everything after the symbol in the line is ignored 3 Variable assignments should be enclosed in quotes VARIABLE value Program Usage A Edit settings below to specify your field of view No comment lines are actually needed an input file setting the necessary parameters could be only a few lines long Horizons Tips for Spitzer Solar System Observers 12 B Mail file as plain text to horizons ss
5. the correct NAIF ID number from the list Horizons gt 606 Horizons will now return satellite physical properties and orbital data for Titan Or For Encke it returns a list of record numbers denoting different apparitions of the comet Select the record number for the apparition within or closest to the Spitzer lifetime Select E phemeris F tp K ermit M ail R edisplay lt er gt 900007 Horizons will return information on this apparition 3 At the prompt choose rz for the ephemeris option Select E phemeris F tp K ermit M ail R edisplay lt er gt e 4 At the prompt choose o for the observer table option Horizons Tips for Spitzer Solar System Observers 3 Observe Elements Vectors 0 e v o 5 Now choose Spitzer as your observatory coordinate center Coordinate center lt id gt coord geo Wspitzer 6 Now choose a date range for the information you want displayed For Spitzer the orbit file extends from launch to approximately 5 years post launch The limits of the current Spitzer orbit file will come up as the defaults for Starting and Ending UT and pressing return on these will ensure that your requested information is calculated for the entire mission duration If you wish to choose a smaller time range make sure that your chosen start and end dates are within the orbit file range Starting UT ex 2003 Aug 25 06 27 2004 Dec 02 00 00 Ending UT ex 2
6. 009 Dec 31 00 04 2005 Dec 02 00 00 7 Next choose a time resolution for the output data Output interval ex 10m 1h 1d 1d Horizons will display the current output table defaults 8 To customize your own output table do not accept the output table defaults Accept default output cr y n n 9 Select the quantities parameters you would like displayed in your output table Typing here will show you a list of 40 possible quantities for display Typing will provide detailed descriptions and information For the Titan example we choose astrometric R A and Dec used by Spitzer for commanding and also returned in the Spitzer data headers satellite X and Y position angle satellite angle separation observatory sub longitude and sub latitude and Sun Observer Target Angle S O T angles between 82 5 120 roughly delineate the Spitzer visibility window However you should use Spot for the final calculation of your visibility windows Or for Encke we choose astrometric R A and Dec observed range and range rate and Sun Observer Target angle For Titan Select table quantities lt gt 1 6 12 14 23 Or for Encke Select table quantities lt gt 2 20 23 Note here that you can also request positional error information for this object s ephemeris by entering or adding 36 37 38 39 or 40 on the table quantity line 36 38 return information
7. 7 chance the object is within a given ellipse assuming measurement errors are random If there are systematic biases such as timing reduction or star catalog errors results can be optimistic Because the epoch covariance is mapped using linearized variational partial derivatives results can also be optimistic for times far from the solution epoch especially for objects having close planetary encounters Displayed results are numerically integrated and include perturbations caused by planets Moon and major asteroids For comets non gravitational outgassing parameters Al A2 A3 DT are also included in the dynamic propagation when appropriate Solar System Dynamics Group 4800 Oak Grove Drive Jet Propulsion Laboratory Pasadena CA 91109 USA Author Jon Giorgini jpl nasa gov For more details on a particular target see the Horizons on line ephemeris system Information http ssd jpl nasa qov Connect telnet ssd jpl nasa gov 6775 via browser telnet ssd jpl nasa gov 6775 via command link Horizons Tips for Spitzer Solar System Observers 11 Note that if this output is reformatted in IPAC table format it can be read as a catalog by the Spitzer Observation Planning Tool Spot and overlaid on Spitzer fits data as a further aid to asteroid identification in Spitzer observations Instructions on formatting a data set in IPAC table format and using it within Spot can be found in the Spot User s Guide under section
8. 97 9 28 8 1994 2004 138 2002 WL7 2 03 16 06 00 32 00 4 19 9 10 15 3 58 396 0 179 2 2001 2004 90 2001 SB182 2 03 25 13 00 18 46 2 20 9 6 15 1 54 422 6 19 6 2001 2004 51 1997 EUA 2 02 50 87 00 46 18 2 20 3 20 64 3 50 1307 9 196 5 1997 2004 103 2001 QD49 12 02 57 52 00 28 46 6 22 4 7 22 2 51 339 5 233 5 2001 2004 28 2001 RP137 2 02 56 62 00 33 50 4 21 8 6 83 1 30 581 2 209 5 1991 2004 33 EXPLANATION OF OUTPUT NUMBER The object s IAU number if assigned NAME OR DESIGNATION The object s IAU name or primary designation RA The predicted astrometric right ascension light time corrected of the object in EME2000 coordinates the J2000 0 system Units DEC in EME2000 coordinates system Units DG MN SC ff Amag T total visual magnitude dRA cosD T observation time with respect to the Earth Mean Equator of HH MM SS ff The predicted astrometric declination with respect to t degrees he apparent visual magnitude of the object hours minutes minutes For comets light time corrected he Earth Mean Equator of the J2000 and seconds of arc of the object and seconds of time Amag is the he instantaneous rate of change of astrometric right ascension at the d RA dt is multiplied by the cosine of the angle of declination to provide a linear plane of sky rate Units ARCSECONDS PER HOUR Horizons Tips for Spitzer Solar System Observers 10 d DEC dt The instantaneous rat
9. Horizons Tips for Spitzer Solar System Observers Document version 4 0 19 Oct 06 The Spot software will return the most accurate visibility windows for your target i e the time ranges over which your target is visible to Spitzer provide time estimates for the execution of your Astronomical Observation Requests AORs and allow you to visualize the orbital path of your target and the execution of your AOR against the infrared background sky as well as submit your proposal and view other accepted program s AORs However Spot does not have the capability to provide more specific geometric information required for planning some Solar System observations To further assist planning your Spitzer observations with Spot the JPL Solar System Dynamics Group has kindly incorporated the Spitzer orbit file into the publicly available JPL Horizons software http ssd jpl nasa gov horizons html Spitzer can now be requested as an observatory within Horizons using the telnet e mail and web interfaces Spitzer s NAIF ID is 79 Consequently Horizons large range of geometric information and observing parameters for Solar System objects can now be calculated for the Spitzer observer The Horizons software suite will now also support 1 user specified clipping of table output over a range of solar elongation angles Solar elongation clipping allows the Spitzer observer to output Horizons observer table information only for times when their object is visi
10. and via the web interface http ssd jpl nasa gov fov html and requires the user to input the Spitzer time of observation and the observed field geometry in one of three different formats polygon circle or rectangle ISPY returns the name of the asteroid its astrometric RA and Dec position Spitzer data headers use astrometric coordinates and information on apparent magnitude apparent rates and characteristics of the data used to create the object s ephemeris ISPY is also implemented through Spot and can be selected in Spot visualization as the Show all known moving objects at a date option in the Overlay menu Here though we provide below detailed input and output files for running ISPY in e mail batch mode and the following simple example illustrates how the program is used Question What are the positions for the known asteroids in the First Look Survey Ecliptic Plane Component 0 degree ecliptic latitude field To answer this we send the following e mail to Horizons with the subject FOV TO horizons ssd jpl nasa gov Subject FOV EMAIL ADDR FOV DATE 2004 Jan 21 13 20 00 TYPE 1 Polygon of four vertices Specify EME2000 RA amp DEC of each of 4 vertices in uniformly clockwise CW or counter clockwise CCW order RA 1 180 71752 EC 1 0 87549 D RA 2 180 54184 DEC 2 0 80378 RA 3 180 92125 DEC 3 0 03310 RA 4 181 08833 DEC
11. ble to Spitzer i e within solar elongations of approximately 82 5 to 120 2 The ability to save program settings between Horizons sessions see Appendix 2 and 3 provides the positions of known asteroids in a given field at a given time as viewed by Spitzer see Appendix 3 A final caveat is that when using Horizons to plan your Spitzer observations we strongly suggest that you also obtain Spot generated visibility windows for your object Spot will always contain the current best knowledge of the Spitzer operational pointing zone which may differ slightly from the nominal 82 5 to 120 definition When using the Horizons output to specify timing or scheduling constraints with Spot ensure that your chosen constraints fall within the Spot generated visibility windows for your object Checking Ephemeris Accuracy Horizons is now also able to provide positional uncertainty information on request for a limited number of objects and typically for targets that are likely to have large uncertainties on positions such as comets and NEOs The step by step instructions in the next section show you how to query the ephemeris table quantities for positional error information for your target quantities 36 40 If positional error information is NOT available for your target n a will be returned Or you can check quickly in the object data sheet for the availability of covariance information denoted by COV after the record number as s
12. d jpl nasa gov with subject header FOV C Results will be returned by e mail in a few minutes depending on system load For more information or to offer suggestions Jon Giorgini jpl nasa gov Solar System Dynamics Group 4800 Oak Grove Drive Jet Propulsion Laboratory Pasadena CA 91109 USA E EMATL ADDR sets e mail address output is sent to Enclose in quotes Null assignment uses mailer return address MATL ADDR FOV_DATE specifies the instantanteous time of the field observation at the spacecraft in UTC FOV DATE 2003 Nov 24 15 20 00 TYPE is an integer indicating which of 3 possible ways the field of view is specified in this file 1 Polygon RA DEC corners of four vertices 2 Circle center amp radius 3 Rectangle center amp RA width amp DEC width amp CCW_angle For all options below RA and DEC may be given in any reasonable format For example the following are all acceptable RA 1 HH MM SS ff DEC 1 DG MN SC f T22317247 20 TSO 18 29 9 22h 17m 47 20s 5d 18m 29 9s spaces between the components are not significant SZ RA 1 DEGREES fffff DEC 1 DEGREES f fff 334 4466666666 5 308305555 1 RA amp DEC values must be in the J2000 coordinate system being with respect to the Equinox and Earth Mean Equator of J2000 0 EME2000
13. e of change of astrometric declination Units ARCSECONDS PER HOUR Cnt Dst The angular distance of the object from the centroid of the field of view Units ARCSECONDS PsAng The position angle of the object relative to the field centroid measured counter clockwise CCW from Celestial North e g line of constant right ascension Units DEGREES Data Arc Years spanned by the astrometry included in the object s orbit solution If less than one year the number of days in the data arc is displayed Nobs The number of observations included in the object s orbit solution This coupled with Data Arc can provide an indication of orbit prediction quality if a formal covariance propagation is not available Error Ellipse Plane of sky POS error ellipse data When available for NEO s comets and objects of special interest these quantities summarize the target s 3 dimensional 3 standard deviation formal measurement uncertainty volume projected into a reference plane perpendicular to the observer s line of sight SMAA 3sig Angular width of the 3 sigma error ellipse semi major axis in POS Units ARCSECONDS SMIA 3sig Angular width of the 3 sigma error ellipse semi minor axis in POS Units ARCSECONDS Theta Orientation angle of the error ellipse in POS the clockwise angle from the direction of increasing RA to the semi major axis of the error ellipse in the direction of increasing DEC Units DEGREES There is a 99
14. een in the example below The data sheet is generated by Horizons and displayed on your screen after step 2 below JPL HORIZONS 33340 1998 VG44 2004 Sep 02 13 23 07 Rec 33340 COV Soln date 2004 Jun 09 11 57 20 obs 51 1998 2003 Generating Spitzer Observer Tables Using The Horizons Telnet Interface Horizons Tips for Spitzer Solar System Observers 2 The following example shows how to use Horizons to determine maximum elongation of Titan from Saturn as viewed by Spitzer or how to retrieve Comet Encke range information as viewed from Spitzer The Titan and Encke examples are run in parallel When both options are shown within a given step this affects steps 2 and 9 only choose one or the other input Titan or Encke The text in bold denotes output from your computer The plain text shows the commands you need to type At each prompt in Horizons typing will return a list of options with brief explanations and typing will return more detailed documentation Please consult the JPL Horizons User s Manual http ssd jpl nasa gov horizons_doc html for a comprehensive description of Horizon s capabilities and instructions for use 1 First connect to the Horizons telnet interface telnet ssd jpl nasa gov 6775 2 At the Horizons prompt specify the target you want to observe Horizons gt titan or Horizons gt encke Horizons found the search string titan for two bodies in this case Choose
15. f e mail batch files for retrieving observer tables instructions on how to save program settings between sessions and how to use the new Horizons ISPY capability to predict the position of known asteroids in your Spitzer fields Appendix 1 Creating Observer Tables Using E Mail Batch Files The same table as generated in our Titan example above can be generated using the following script to generate the Encke example substitute 201513 for 606 and substitute 2 20 23 for 2 6 12 14 23 Note that leaving EMAIL ADDR blank will default to returning results to the originator s e mail address or you can explicitly specify an e mail address here Note that if your specified table is particularly long the results may be e mailed back to you as a series of e mails Example for Titan satellite 606 SSSOF Example e mail command file If mailed to horizons ssd jpl nasa gov with subject JOB results will be mailed back This example demonstrates a subset of functions See Horizons User s Guide for l l l full explanation l EMAIL ADDR Send output to this address COMMAND 606 Target body OBJ DATA Yes Summarize target body MAKE EPHEM Yes Make an ephemeris TABLE TYPE OBSERVER Set ephemeris type to OBSERVER table CENTER Spitzer Set observer coordinate center
16. on the object s positional uncertainty in the plane of the sky and 39 40 return information on the object s range uncertainty Typing at the above prompt will give a more detailed description of these quantities Note also that not all targets have quantities 36 40 available and will return n a if that is the case Horizons Tips for Spitzer Solar System Observers 4 10 Output reference frame should be J2000 the default hit return Output reference frame J2000 B1950 11 Accept the default time zone correction just press return Time zone correction UT 00 00 12 Select the output UT time format Calendar format is the default Output UT time format JD CAL BOTH 13 Select the level of precision of the output time format To the nearest minute is the default Output time digits MIN SSEC FRACSEC 14 Choose R A format in fractional degrees or hours minutes seconds Output R A format HMS DEG deg 15 Choose between 10 arcsec and 10 arcsec precision for R A and Dec output Output high precision RA DEC YES NO y 16 Because the observatory is Spitzer the airmass model elevation rise times and daylight options do not matter Accept the default parameters hit return on all of these Output APPARENT I Airless Refracted Minimum elevation 90 lt elv lt 90 Maximum air mass 1 lt a lt 38 Prin
17. t rise transit set only N T G R Skip printout during daylight Y N 17 Choose the range of solar elongation angles you would like the output over e g specifying the range 82 5 to 120 degrees solar elongation mimics the Spitzer operational pointing zone the range of solar elongations over which Spitzer is permitted to point The default is all solar elongations Solar elongation cut off 0 180 82 5 120 18 Choose whether you want the output table columns separated by spaces N or commas Y Comma separated entries are easier to read into spreadsheet programs like Excel Spreadsheet CSV format Y N Y 19 You are now the proud owner of a Horizons generated observer table Explanations for all the parameters you selected are found at the bottom of the table Step through the table or hit q to exit Horizons Tips for Spitzer Solar System Observers 5 from display of the table You can now either e mail the table to yourself or ftp the table from Horizons Choose gt gt gt Select A gain N ew case F tp K ermit M ail R edisplay m and enter your e mail address at the prompt or gt gt gt Select A gain N ew case K ermit M ail R edisplay f and Horizons will tell you where to ftp to and the filename for your observer table You have 30 minutes to retrieve your file The following appendices describe the creation o
18. ved example 79 Spitzer Space Telescope 13
19. with command DELETE Fo them CYPE Start to existing name observing location the target R r example Settings for For macro names NAME Replace with a SAVE Note that start stop dates are also saved in the macro You need only load the macro and select emaining defaults will be as defined in the format etc macro If your macro is for an individual address Otherwise don t future If your last the other tabl Delete and replace a confirmation password LOAD does not that table type will be saved as the default operations require input of as is you can set the e mail and you will be prompted for it in the table prior to saving the macro was a vector table table saved as well so to access types ar you would manually respond to the prompt requesting table over riding the macro s vector default on that issue and stop times are also macro settings that may commonly be overruled as necessary but call them what you want I recommend something clean and logical OBS670 1 for macro 1 for Observatory Code 670 etc Horizons Tips for Spitzer Solar System Observers 8 Appendix 3 ISPY Determining the Positions of Known Asteroids in Spitzer Fields As of 5 04 Horizons can now determine the positions for known asteroids as seen by Spitzer This new tool ISPY can be run both in e mail batch mode
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