Home

Here

1. This command adds your Offset values onto the Dial field while the Offset goes to zero Since the Dial values were all zeros and you have incremented your offsets onto those zeros you did not move the telescop The pointing should now be close to correct Test it by going from the bright star you are currently on to another target that will be bright enough for you to be sure what you are looking at either another bright star or a science target of yours that you will be able to see in the finder scope or with you instrument If not dead on the telescope should have landed much closer to this second target Enter whatever smaller additional offset is needed either by paddle or keyboard to get this second object centered either in the finder scope crosshairs or at the same position on the image for an imaging instrument If using an instrument with an aperture or a slit position the source on that aperture or slit When you are sure you are getting signal through the system go to the two finders and adjust the crosshairs so that the image is in the center Now the additional smaller Offset should be incrementally added to the existing Dial field values by repeating the command IDIAL lt Enter gt REMINDER From now use IDIAL only not DIAL If you use DIAL that will wipe clean the first amount of Offset you transferred into the Dial field and will mov th telescop becaus by swapping out one Di
2. SUPPLEMENT TO UNIVERSITY OF MINNESOTA USER S MANUAL for MOUNT LEMMON OBSERVING FACILITY MLOF a k a MINNESOTA 60 TELESCOPE Updated as of 2014 Oct for questions contact Dinesh Shenoy Graduate Student Minnesota Institute for Astrophysics University of Minnesota 116 Church St SE Tate 356 Minneapolis MN 55455 612 710 7746 shenoy astro umn edu This document describes procedures for starting up the MLOF telescope also commonly referred to as the Minnesota 60 telescope This document supplements the August 1997 University of Minnesota User s Manual A copy of the User s Manual is kept on th telescop operator s desk The User s Manual is also available online at http ir astro umn edu telescopes mlof protected forth tcs manual pdf This supplement will cite particular pages in that main manual as e g User s Manual p 11 TABLE OF CONTENTS SECTION 1 BEFORE POWERING UP THE TELESCOPE IN THE DOME 2 SECTION 2 STEPS FOR THE FIRST NIGHT OF OBSERVING 2 SECTION 3 MOVING TO YOUR FIRST TARGET OR A BRIGHT STAR 7 SECTION 4 RE ESTABLISHING POINTING 10 SECTION 5 END OF NIGHT PROCEDURES 14 SECTION 6 START OF SECOND AND SUBSEQUENT NIGHTS 14 SECTION 7 LIGHTNING SHUTDOWN 16 SECTION 8 TROUBLESHOOTING 16 SECTION 9
3. The days number on the Datum clock is irrelevant You check the amber monitor and its says UTC DATE 24 30 30 April 2014 14 Although it says the day is still 30 April 2014 the software has compensated by extending the time beyond 24 hours Give the following command to increment the day NEW DAY lt Enter gt This increments the day by one and subtracts 24 hours from the UT If you do not give the NEW DAY command and instead just proceed to observing with the SEEK command to move to a target entered in one of the catalogs the telescope will first xecut th NEW DAY command before moving to the new target see User s Manual p 8 describing the SEEK command In this case you should see the date advance by one day and see 24 hours subtracted off the UT It is 4 30pm on 30 April 2014 in Tucson The telescope shows UTC DATE 23 23 00 30 Apr 2014 That is the correct UT Time and Date An hour later it is 5 30pm on 30 April 2014 in Tucson Therefore the UT time and day are now 00 30 on 1 May 2014 Again the Datum clock will always have the correct hours and minutes as long as it was not powered off and the days on it are irrelevant However when you check the amber monitor you see UTC DATE 00 30 30 April 2014 In this instance the software has not advanced the dat when the tim flipped over from 23 59 to 00 00 hours It has the correct Universal Time in hou
4. OTHER USEFUL INFORMATION 17 SECTION 1 BEFORE POWERING UP THE TELESCOPE IN THE DOME Before starting up the telescope all electronic cables in the control room and dome must be reconnected There are two slim red softcover booklets on the shelf over the desk to your left as you enter the control room from the machine shop These have pictures and short descriptions of the various connections If this is your first time connecting the cables please consult either University of Minnesota personnel or Steward Observatory personnel for guidance Whenever opening or closing the dome slit the primary mirror should be covered up The covers are two wooden flaps which are raised and lowered by ropes tethered to the NE and NW sides of the telescope The west side flap should be raised first and lowered last If you open the dome slit part way during the day time to let some light into the dome whil you are working in there make sure the primary mirror is covered up and never exposed to direct sunlight The burn mark on the southern wall of the dome speaks for itself The telescope balance weights must be properly adjusted for whichever instrument is mounted on th telescope Th telescop motors can be damaged if the telescope is out of balance and you attempt to observe at an hour angle or declination that puts strain on the motors In addition being out of balance can leading to pointing er
5. elsewhere Selecting an object from a catalog The computer has ten catalogs numbered 1 through 10 If this is your first time using this telescope it is recommended that at least once or twice you enter a target s coordinates manually with the PRECESS command and become familiar with some of the messages and displayed information discussed in the previous subsection Once you are comfortable with the basics using the catalogs including creating your own entries is desirable and cuts down on the chances of making a typo when entering coordinates with the PRECESS command Here is an example of using the 8 catalog which contains many bright stars Load this catalog with the command 8CAT lt Enter gt To see all the stars in this catalog type ALL lt ter gt m Ho To scroll through the catalog hit the Enter key Any key besides Enter exits the catalog and returns the cursor so that you can choose your desired catalog entry or enter other commands The bright stars in 8CAT are listed in ascending RA order Once you find a bright star that you want to go to hit Space to exit the scrolling and get the cursor back Then enter that star s catalog number followed by the SEEK command For example in 8CAT alpha Orionis Betelgeuse is star number 120 so to go alpha Ori you enter 120 SEEK lt Enter gt and the telescope slews to alpha Or
6. While observing or at the end of the night it is the observer s responsibility to periodically check the weather forecast Looking at both the National Weather Servic forecast and a local news website with Doppler radar is a good idea If there is a threat of thunderstorms at any time whether day or night in particular while all observers may be asleep the telescope must be put into lightning shutdown If in doubt about whether or not thunderstorms are approaching to be safe you should put the telescope into lightning shutdown The following steps are mandatory e Return the telescope to Zenith cover the primary and close the dome slit e Switch back to Manual on the TDC panel e Switch off the Chopping Secondary and the power supply amp Amps below the desk e Exit the TCS software with the BYE command and turn off the TCS computer just shut off the green switch e Turn off Main Power Do any required lightning shutdown tasks for the instrument you are using e g 2MASS has certain lightning shut down procedures e In the control room disconnect all cables labeled Disconnect in the Event of lightning which are indicated in the Pictures e In the dome disconnect all the cables labeled Disconnect in the Event of Lightning These include both RA and Dec motors and encoders the dom ncoder over th door the connections in the pier and the connection in the blue tower to the west of the pier
7. be one day ahead of your local date If the telescope does not have the correct UT month or day of month use the EPOCH command to correct it For example suppose the current UT date is 28 April 2014 but the Date field shows 23 June 2013 Enter 28 APR EPOCH lt Enter gt That updates the day to read 28 April 2013 In giving the EPOCH command the month is always the first three letters of the name of the month If the year is wrong correct the year with the A D command 2014 A D lt Enter gt Note that periods are required in A D For more on the EPOCH and A D commands see User s Manual pp 7 8 Once the date is correctly displayed in the upper right of the main monitor you can enter 2TERM lt Enter gt This command activates the amber monitor It transfers all the telescope status information object you are pointed at its RA Dec etc from the main monitor over to the amber monitor Using 2TERM to display the telescope s current target frees up the main monitor for editing viewing catalogs and entering commands NOTE It is recommended that you do this verification of the date and time 4 while in 1TERM mode At the end of Step 5 you could have typed the 2TERM command to immediately bring up the telescope status on the amber monitor However if you did so and then noticed the date or time on the amber monitor was not correct xperienc has shown that even if you g
8. provide better pointing than Col For reasons why Col might be preferred see User s Manual p 11 Continuing with this scenario suppose that to get pointed dead on your target you accumulated the following offsets OFFSET 0 06 34 2 0 01 04 9 Add your Offsets incrementally to the current Dial values with the command IDIAL lt Enter gt See User s Manual p 11 This command adds your Offset values onto the existing Dial values factoring in cos Dec for the RA offset The telescope continues to point at the same position and your Dial value has been adjusted to include the Offset you determined that you need and now the Offset field is back to zeros When you move to your next target the additional offset that you IDIAL d in should give you better pointing For subsequent targets you can repeat this procedure of IDIAL ing in any offset you find you need to point properly NOTE The IDIAL command is distinct from the DIAL command In the present scenario wher there wer xisting non zero Dial values and the pointing was close to desired but needed some additional correction you want to use the IDIAL command not the DIAL command Scenario 2 In this scenario you are unable to find your target in the finder scopes and after trial and error movement with the paddle or by 11 entering offsets on the keyboard Or you have found your target but only by entering Offsets of several degrees There are several
9. steps to take at this point e Double check that you have the correct UT time on the Datum clock since the wrong time will throw off the pointing Double check the date for the same reason If in fact the date or time is wrong repeat Step 6 above e Double check the coordinates you entered for the target If leading zeros were omitted you could be pointing somewhere other than your actual target If neither of these user errors were the source of the pointing problem then it is best to establish the pointing anew Return to Zenith by entering ZENITH lt Enter gt Then zero out any Offset and reset the turn counters with the commands ZERO INDEX ZENITH GO lt Enter gt the commands can be given all at once At this point the Offset fields contain all zeros Transfer all those zeros into the Dial fields with the command DIAL lt Enter gt Note this is the DIAL command not the IDIAL command Instead of incrementing the Dial value giving the DIAL command wipes out any previous Dial value and replaces it with the value that was in the Offset fields This is the only time to use the DIAL command You have just zeroed out the Offsets and want to zero out the Dial fields as well After this you will not be repeating the DIAL command instead you will use the IDIAL command If the Col values are non zero zero them out as well using the COL command per User s Manual p 11 So at th
10. the printer That is the monitor on which you will start up the software and enter commands to move the telescope Hereafter it will be referred to as the main monitor The smaller monitor that sits on the shelf above the TCS computer is an amber monochrome monitor the brand name is GoldStar This monitor will be used to display the object at which you are pointing its RA Dec offsets etc and other telescope housekeeping data Hereafter it will be referred to as the amber monitor STEP 5 The TCS takes several seconds to boot up It is ready if it displays the following messages C gt C DOS SMARTDRV EXE X Device driver not found BANANA No valid CDROM device drivers selected C 32MLOF07 gt If you do not reach this command prompt and instead s a messag X keyboard not detected check the back of the TCS computer to see if the keyboard s cable has come loose Re seat it and restart the computer Turn CAPS LOCK on At the C 32MLOFO7 gt command prompt type PF and hit enter C 32MLOF07 gt PF lt then hit Enter gt That loads the polyForth nucleus giving a new command prompt that appears as follows pF32 386 pMSD 08 Feb 1994 Copyright C by FORTH Incorporated hi At the prompt hi enter MLOF to load the software specific to MLOF hi MLOF lt Enter gt A number of messages flash past the software has loaded properly when you get the following line fol
11. Consult the red soft cover booklets with the pictures SECTION 8 TROUBLESHOOTING The following are some problems that uses have encountered with recommended solutions e In Step 5 above when you enter MLOF you do not get th messag Today is 1 Jan 1950 Time 19 13 pF32 386 pMSD 08 Feb 1994 ok with a blinking cursor Instead the main monitor shows it is hung up at some stage in the process of communicating with to any one of several devices such as the Clock MUXes multiplexers lock in amplifier printer etc Generally this is a sign that one or more cables has not been re connected properly Turn off Main power and the TCS computer consult the red booklets of photos for the cable connections and connect any missed cable s Then turn Main Power and the TCS back on and proceed with Step 5 16 A bright star is centered in the finder scope cross hairs but cannot be seen on the instrument Check the Chopping Secondary panel in Rack 1 The panel must be On and the switch at the top middle of the panel should be in the coll position meaning collimate the beam rather than chop the beam If the Chopping Secondary panel is off then the secondary mirror is likely tilted at some angle and your instrument was instead receiving light from off to one side of the bright star The telescop moves to point at a target but the dome does not move to match its position Mak sur the power cord for op
12. Section 6 below e If no thunderstorms are predicted you can leav th telescop cabled up and powered up with the following specific switches turned off On the RA and Dec Drive Power Amps below the desk switch each to Motor Offa On the TDC panel switch from Computer Control to Manual Turn the Chopping Secondary Panel off Leave the Tilt Indicator panel on it is your way of knowing whether th telescop has been moved independent of any information on the amber monitor e In the dome first cover up the primary mirror Then close the dome slit raising the lower panel while the slit cover comes down from the top Disconnect the power to the slit motors once the slit is fully closed If the instrument you are working with has any special end of night procedures perform those as well consult the instrument team for specifics SECTION 6 START OF SECOND AND SUBSEQUENT NIGHTS Before the start of observing on your second and subsequent nights verify that the telescope knows the current UT Date This is best done shortly after 5pm when the next UT Day has begun Two common scenarios are encountered 1 It is 4 30pm on 30 April 2014 in Tucson The telescope shows UTC DATE 23 30 30 Apr 2014 That is the correct UT Time and Date An hour later it is 5 30pm on 30 April 2014 in Tucson Therefore the UT time and day are now 00 30 on 1 May 2014 The Datum clock correctly states the time as 00 hours 30 minutes
13. T INITIALIZE Please note The main User Manual has an error in the discussion of contract on page 28 It should read lt n gt contract shifts the lt n 1 gt th and subsequent records up one slot The original contents of the lt n gt th record are overwritten and lost SECTION 4 RE ESTABLISHING POINTING If th telescop does not point at your first target whether a science target or bright star the pointing should be re established or established anew This section discusses two scenarios Scenario 1 The pointing is off but you have been able to find your object or bright star either looking through one of the finder scopes or by seeing your object with your instrument Since you landed close enough to your object you are able to get yourself pointed dead on using either the paddle or keyboard commands to make Offsets in RA and Dec The needed offsets should be no more than 30 seconds of arc in either coordinate Scenario 2 You are unable to find your object whether in the finder scopes or by seeing it with your instrument Or if you did find your object by moving around in a search pattern you accumulated Offsets of 10 several degrees or more These two scenarios will be discussed in order Scenario 1 If the telescope pointed close enough that you were able to get positioned on your object with Offsets of no more than about half a degree in RA and or Dec then you may be able to r stablish point
14. al value for a brand new one the telescope purposely forgets about the first Dial d in value and understands you to be giving it a new offset to work from See User s Manual p 11 the only occasion to use DIAL is as directed above to wipe clean the Dial fields by replacing them with Offsets all zeros After that use IDIAL only 13 Proceed with observing your targets As you move around the sky on this and subsequent nights if you find you need some additional amounts of offset to keep pointing correctly you can keep adding them incrementally to the Dial field with IDIAL Note if while you are on a target you accrue some Offsets due to deliberately moving the object around e g to purposely sample different parts of an array then befor leaving that target you probably want to undo those offsets rather than IDIAL ing them in before moving to the next target In other words before leaving your current object return yourself to the same pointing as when you arrive at the object SECTION 5 END OF NIGHT PROCEDURES e Return the telescop to Zenith Whether you leave in any accumulated Offsets or not is up to you I usually clear them e Consult the latest National Weather Servic forecast and a Doppler radar website and assess if there is any risk of thunderstorms between the end of the current night and the start of the next night If thunderstorms are predicted you MUST perform a lighting shutdown see
15. alues in the Offset fields they now read all zeros User s Manual p 10 STEP 11 The telescop keeps track of how much it has moved in RA and Dec by counting the turns of two worm gears one for RA one for Dec The number of turns that the worm gear has made is tracked by counters in the software Since you are starting at Zenith you want to re index those counters and tell the telescope that it is at Zenith INDEX ZENITH lt Enter gt these two commands can be entered on a singl line Then turn tracking on with GO lt Enter gt The telescope will not actually move yet for two reasons 1 You are still in Manual on the TDC Panel not Computer Control Mode and 2 Zenith does not move with respect to the telescope mount ground When you turn control over to the computer and tell it to go to some object other than Zenith having given the GO command will enabl the telescope to move Check the Errors fields on the amber monitor They should be less than 1 degree each If not repeat Steps 9 11 If yes proceed to the next step STEP 12 On the Telescope Drive Control panel flip the switch up from Manual to Computer Control Mode The RA Drive Pre Amp will beep once and the telescope will make a small move away from where you had positioned it This is normal The Tilt Indicator for the RA will increase to a value of around 0 009 or so and the Dec s tilt ind
16. compute precession matrices so it is important to get the time accurately programmed The telescope control computer s internal clock keeps th tim onc th Datum clock has been read at start up The UT calculated by the computer should always agree with the Datum clock while you are observing STEP 2 On the Telescope Drive Control TDC panel verify it is in Manual not Computer Control Mode STEP 3 Below the desk by your feet is the Secondary Mirror Power Supply 24V Power Supply Verify that it is Off Also down ther ar th Dec Drive Power Amp and the RA Drive Power Amp On these two Power Amp units verify the switches are in the Power Off and Motor Off position STEP 4 Turn on Master Power which is the switch located in the bottom right corner of the Master Control Panel Turn on the Telescope Control System TCS computer which is the PC located in the middle of the blue rack The On switch is green it lights up Turn on the power strip located next to the monitor in the blue rack The power strip and monitor sit ona shelf above the computer and below the lock in amp Turn on the lock in amp that is located immediately below the Datum clock Turn on the Tilt Indicator panel Turn on the speaker the black box that sits on top of Rack 1 into which the Dome Microphone cable is plugged There are two computer monitors The main computer monitor is a grey monochrome AcerView 56L monitor that sits below
17. d RA hh mm ss ss 07 45 18 95 DEC dd mm ss s 28 01 34 3 The telescope will then compute the matrices needed to precess these coordinates from January 1 2000 to the present date time It displays these as the Wanted coordinates on the monitor just above the J2000 0 field Note that the Actual coordinates which it points at depend on whether or not you have any values in the Offset fields Actual Wanted Offset This relationship between what is displayed in the Actual Wanted and Offset fields is readily apparent for the Dec column on the amber monitor because all three Dec fields are measured in degrees minutes and seconds of arc For the RA column this relationship Actual Wanted Offset is equally true but remember that on the amber monitor RA Offset is displayed in degrees minutes and seconds of arc while Actual and Wanted RA are displayed in hours minutes and seconds of time NOTE Leading zeros on single digit numbers must be included when ntering coordinates If you forget to enter a leading zero the telescope will misunderstand where you want to send it Continuing with the preceding example suppose instead I had typed beta Gem s Dec as DEC dd mm ss s 28 1 34 3 Th telescop interprets that as 2 degrees 81 minutes 34 3 seconds of arc which equals 3 degrees 21 minutes 34 3 seconds and proceeded to move to Dec 03 21 34 3 instead So it is very im
18. d on If you don t set the RA and Dec Power Amps to Motor On you cannot do the next step Turn on the Secondary Mirror Controller above the focus read out red LEDs STEP 9 Using the paddle zero out the Tilt Indicators You can move Simultaneously in the N S and E W directions There are 3 speeds at which you can mov th telescop s User s Manual p 10 Th fastest speed is Slew speed which is what you want to use for this step Hold down the Slew button while pushing the N S E W buttons You do not have to get the Tilt Indicators to exactly 0 000 values of 0 003 or so are sufficient NOTE The Tilt Indicators are independent of the TCS They are pendula that provide their values based solely on how far the telescope is physically tipped over in the RA and Dec axes They also provide independent information about whether or not the telescope is moving regardless of what the TCS displays on the monitors STEP 10 Using the paddle to zero out the Tilt Indicators accumulated some Offset in either RA or Dec In addition there may be lingering offsets from the previous use of the telescope If you set the telescope so that the tilt indicators read 0 009 RA and 0 000 Dec then it is unlikely that the scope will move later when you switch to computer control Keep an eye on these Offset fields while you enter the following command ZERO lt Enter gt That command erased any v
19. ening closing the slit has been disconnected It is a safety feature to prevent the dome from turning if the slit motor is still plugged in Make sure that computer control of the dome has been turned on by entering the ONDOME command User s Manual p 33 In the unlikely event of a loss of power while pointing at an object other than Zenith the TCS the computer may reboot If this occurs put the system in Manual on the TDC panel Because of the reboot the TCS computer does not know wher th telescop is currently pointing Repeat Steps 5 through 11 above in Section After completing Step 11 return from Manual to Computer Control Mode on the TDC Panel and go back to your object As of 2014 April when th telescop is at Zenith and the dome has rotated around to position angle 180 the 4 prong outlet cord no longer reaches far enough over to the plug that connects to the two switches to raise lower the slit and the lower panel on the slit This is because the conduit that holds the wires leading from the slit motors to the switches has gotten bent likely as a result of the dome being rotated and catching on a ladder that was not stowed far enough away from the wall The result is that to connect the slit motors to their 4 prong power cord the dome needs to be rotated by about 10 to position angle 190 If you are in Computer Control Mode go to Manual mode and rotat th dom over close enough to reach the power cord Af
20. ever if the telescope running away is due to a software glitch these computer commands might not work and so the most sure fire way to stop the telescope from moving is to flip from Computer Control Mode to Manual SECTION 3 MOVING TO YOUR FIRST TARGET OR A BRIGHT STAR You can now move to your first target or a nearby bright star e g if you want to assess the pointing with something unmistakably bright instead of starting on what might be a dim science target There are two ways to move to an object 1 enter the coordinates manually or 2 select the target from one of the catalogs either th pr xisting catalogs or your own additions to catalog 7 discussed further below Entering coordinates manually If you are new to this telescope it is worth at least once entering the coordinates manually before turning to use catalogs For xample her is how to manually move to beta Gemini Type PRECESS lt Enter gt The telescope asks Following co ordinates assumed to be J2000 0 Continue Y N As long as you are indeed going to supply it with beta Gem s J2000 coordinates answer Y You are prompted for a Name which is optional it is for you own reference this name will appear on the amber monitor You are prompted to enter the RA and the Dec PRECESS Following co ordinates assumed to be J2000 0 Continue Y N Yes Name enter its name if you want not require
21. i NOTE All catalog entries have a column E for Epoch A number 1 in this column indicates that the RA and Dec for an object are B1950 coordinates A number 2 in that column indicates J2000 coordinates The telescope is always set to one or the other epochs this determines the dat from which it computes precession matrices to the present day coordinates for any target see User s Manual pp 13 14 The epoch to which the telescope is set is shown on the status screen on the amber monitor It is the line below Wanted it reads either J2000 0 or B1950 0 Most likely this field is labeled J2000 0 becaus the previous observer s last target most likely was entered in J2000 coordinates If you select a bright star in 8CAT whose coordinates are B1950 when you enter the SEEK command the computer will beep and give an Epoch Mismatch message It asks if you want to change the epoch from J2000 to B1950 ALPHA ORI 5 52 27 80 7 23 58 0 EPOCH MISMATCH Change epoch to B1950 0 and go to source Y N This is not an error message it is simply the telescop telling you that it is going to precess the catalog entry s coordinates from January 1 1950 to the present moment rather than precess them from January 1 2000 Enter Y to answer Yes and the telescope will precess the B1950 coordinates to the current date and time and will go to that object No
22. icator may increase slightly as well After that the telescope will wait for you to give it a command to move away from Zenith see next section The RA and Dec Pre Amps emit beeps whenever the computer is moving the telescope at th Slew speed th fastest speed This is to alert you to pay attention to whether the telescope is going where you intended it to 6 If the telescope starts to run away on you go back to Manual When switched from Manual to Computer Control Mode there is the possibility that the telescope will run away i e steadily move in some direction in RA and or Dec even though it should still be pointed at Zenith You know the telescope is running away if either the RA or Dec Drive Pre Amp continues to beep and the Tilt Indicators show one or both of the values steadily changing despite the fact that the current target is Zenith Once you have halted the movement of th telescope consult the troubleshooting section below and or contact the University of Minnesota Running away could be due to a cable not being properly connected or a communication problem between the multiplexers in the dome and control room or some other issue Note An alternative to stopping the telescope by flipping from Computer Control Mode to Manual is to give any one of the following commands FREEZE lt Enter gt STOP lt Enter gt HALT lt Enter gt See User s Manual p 9 How
23. ing simply by adding your offset incrementally to the existing Dial offset Per Step 7 above the existing permanent offsets at the time of start up are contained in the Dial and Col fields Suppose that when you started up the Dial and Col fields held the following values COL 0 00 00 0 0 00 00 0 DIAL 0 33 56 4 Or TEIGE When you gave the ZERO command in Step 10 you set the Offset fields to zero before moving away from Zenith The Dial and Col fields were left untouched They contain these values based upon the pointing established by the previous user The Dial values I hav depicted her ar usual values for good pointing Dial and Col are each a kind of offset The full explanations are given on User s Manual pp 10 11 The general practice of most observers in the past few years is to keep the Col fields at zero and use only the Dial fields This is because Dial accounts for the cosine Dec factor required when taking into account th differenc between offsets in RA depending on whether you are observing close to the celestial equator or farther North South Visualize lines of constant RA converging at the North Celestial Pole moving th telescop ast or west by say 30 seconds of time West requires a smaller physical angular move of th telescop when pointed close to the NCP than when pointing near the equator Therefore when observing over a wide range of RA and Dec throughout the night Dial should
24. is point you should have the following OFFSET 0 00 00 0 0 00 00 0 COL 0 00 00 0 0 00 00 0 DIAL 0 00 00 0 0 00 00 0 Now send th telescop to a bright star that is close to Zenith A good choice is the alpha star in a constellation close to Zenith because it will be unmistakably bright in the finder scopes You can find a bright star close to zenith by scrolling through the bright star catalog 8CAT see previous section or use the current Astronomical Almanac s Section H list of bright stars Note if you use the Astronomical Almanac beware that they give coordinates precessed to the middle of whichever year the Almanac covers I use the Almanac only for identifying a bright star in a particular part of the sky I then look up its J2000 coordinates elsewhere With Dial all zeros the telescope s pointing will be off by about half a degree Look for your bright star in one of the finder scopes The alpha star of a constellation is easily seen if it is the finder scope Note that the finder scope on the North side of the telescope has a field of view approximately half a degree in radius the South scope s f o v is slightly larger Therefore the star might be just on the edge of the field of view 12 If you can see no bright star in the field of view paddle back and forth in one direction first and then the other Once the bright star appears somewhere in the finder scope f o v get it centered in the cross hairs The cro
25. ive the EPOCH and A D commands to tell th telescop the correct day month and year the new values you enter with EPOCH and A D do not refresh on the amber monitor Thus if you have gone to 2TERM mode and see the day month or year is wrong it is recommended you go back to 1TERM mode issue the EPOCH and or A D command to correct the day month and or year and then go back to 2TERM mode STEP 7 Make note of the current values of Offset Dial and Col in both the RA and Dec columns on telescope status screen which is now displaying on the amber monitor if you did 2TERM In normal operation when the telescope has been pointing properly for the previous user and you are now starting off as always with the telescope pointed at Star 1 Zenith thes thr fields in the middle of the display will typically appear as follows OFFSET 0 00 33 0 0 01 00 0 COL 0 00 00 0 0 00 00 0 Figure 1 DIAL 0 33 56 4 0 18 56 3 The Offset field might be all zeros or it might have some non zero values as in this example NOTE On the telescope status screen the RA column fields for the Actual Wanted and J2000 0 Right Ascension for your object are given in sexagesimal notation hours minutes and seconds of time This is done so that the user can easily verify the coordinates they hav ntered for their target usually J2000 coordinates possibly B1950 coordinates can see what
26. lowed by a blinking cursor Today is 1 Jan 1950 Time 19 13 pF32 386 pMSD 08 Feb 1994 ok If you do not get this message s the Troubleshooting section below Enter TELESCOPE LOAD lt Enter gt Som mor messages scroll past and you reach a screen listing several different commands with explanation of what they do The final line says T MAIN OR HELP Return to this MAIN HELP index screen ok Wait for the blinking cursor once it appears the telescope is ready to accept commands STEP 6 The next step is to make sure the telescop knows the correct UT Date Having an inaccurate date is a common source of pointing errors To check that the telescope has the correct UT date enter 1TERM lt Enter gt Note that as you have the caps lock on this is the numeral 1 and not a lower case L That command brings up telescope status information on the first 22 lines of the main monitor It leaves a few lines at the bottom for accepting commands In the upper right of th screen verify that the telescope has both the correct UTC in hours minutes as well as the correct date Arizona is always 7 hours behind UT For example at 2 15pm on 27 April 2014 the UT time date is 21 15 27 April 2014 At 5pm in Arizona the UT date flips over to 00 00 on 28 April 2014 Thus depending on whether you are starting up before or after 5pm local time the UT date might be the same local date in Arizona or might
27. portant when manually entering coordinates to check th amber monitor and make sure the J2000 0 field in fact contains the coordinates you intended In this example since the telescope starts moving to the wrong declination I immediately enter STOP or HALT or FREEZE lt Enter gt I then re enter my PRECESS command with the leading zero included and the telescope begins moving again this time to the correct coordinates What if you make a typo while entering the PRECESS command E g you want to skip typing in a name for your object then wind up typing your object s RA into the name field then type the Dec into the RA field and then enter a blank Dec field Go ahead and hit Enter to get through the fields and back to the cursor If the telescope starts to move having tried to interpret the erroneous coordinates entered just type STOP or HALT or FREEZE and re do the PRECESS command properly and it will go to the new corrected coordinates ELEVATION LOWER LIMIT The telescope has an elevation lower limit of 12 degrees If by mistake you try to send it to an object below this limit e g the object is below the horizon the telescope will not move and will instead give this message ELEVATION BELOW 12 DEGR T E LIMIT The telescope will wait in its current position to be commanded to move
28. rors or sporadic jerking that smears images If you are uncertain whether the telescop has been balanced for the instrument you are working with contact UMN or Steward Observatory personnel In general the responsibility for balancing the telescope will have been discussed prior to your arrival and will depend on which instrument you are observing with If you do not know if the telescope has been balanced do not observe with it until contacting us SECTION 2 STEPS FOR THE FIRST NIGHT OF OBSERVING This section discusses steps to take prior to opening up for your first night of observing STEP 1 Turn on the Datum clock and set it to the current Universal Time UT The Datum clock is located in the blue rack to the left of the telescope operator s desk labeled Forth Computer Rack Get the current UT from one of the following sources e Call NIST s WWV clock at 303 499 7111 it is on the speed dial e Google universal time and find a reliable source such as the US Naval Observatory s online clock Set each red LED digit by turning the black slow code wheel to the desired number then pushing the small black button under that LED When you are ready to start the clock at a time that coincides with the current UT push the little black start button located to the left of the on off switch on the clock When the telescop software is started up it will read in this time and use it to
29. rs and minutes but being a day behind will throw off the pointing because the telescope thinks the Earth is 1 day behind where it actually is in its orbit around the sun In this scenario you must manually correct the date Try this command NEW DAY lt Enter gt If this incremented the day and the UT continues to be the correct hour minute you can proceed to observing If the date is still not correct types 1TERM lt Enter gt to bring the telescope status screen to the main monitor Enter the corrected date which in this example would be 01 MAY EPOCH lt Enter gt No need to change the year with the A D command since the year already is 2014 If the pointing has been incorrect this should correct it You can go back to 2TERM mode The reason I go to 1TERM mode is that when I ve been in this scenario and used the EPOCH command to update the day and month if I stayed in 2TERM mode the dat does not update on the amber monitor even though the telescope knows the correct day and month now By fixing the day month with the EPOCH LS command while momentarily in 1TERM mode and then going back to 2TERM mode the date field on the amber monitor refreshes properly By checking the UT day and if you are in Scenario 2 correcting it shortly after 5pm local time you should have the same pointing for that night as for the previous night SECTION 7 LIGHTNING SHUTDOWN
30. ss hairs can be illuminated by flipping on the switch on the small black box along the barrel of each finder scope make sure the light s power supply is plugged in For scale the cross hairs in the North finder scope measure 7 5 in length When moving the telescope to get centered on the star it is best to use the SET speed button To move at SET speed hold down the button that is along the top edge of the paddle while also holding one of the NSEW buttons Without the SET speed button pushed down the NSEW buttons move very slowly for such a wide field of view but fast enough for fine guiding on a tracked object The Slew speed moves very rapidly making it easy to lose an object in the finder scope By getting your object centered in the cross hairs you have created Offsets that should be about 30 arcminutes in RA and about 20 arcminutes in Dec You could simply operat the rest of the night from this offset position e g if you make any further moves onto around your objects then befor leaving for your next object you would take out those offsets by just the right amount to return to your current offsets A better plan is to move your Offsets into the Dial field using IDIAL where they will be held as a permanent pointing correction Since right now the Dial field contains all zeros you can add your Offsets onto the Dial field and maintain your pointing with IDIAL lt Enter gt
31. te that on the amber monitor under Wanted the next field below it now reads B1950 0 After you are done with this target if the next target you go to is given in J2000 coordinates then when you enter the command to move to that next target the computer will giv th sam poch mismatch message Respond yY for Yes and it will switch back to J2000 coordinates for computing the precession and moving to your next object Putting your targets into a catalog You can add your own catalog entries for your targets standards Please use 7CAT for your entries DO NOT MAKE OR DELETE ANY CATALOG ENTRIES IN 8CAT THE BRIGHT STAR CATALOG ALSO 9CAT IS RESERVED FOR THE AEROSPACE CORPORATION PLEASE DO NOT MAKE ANY CHANGES ADDITIONS TO 9CAT If the previous observer left any entries in 7CAT delete them with the command 7CAT INITIALIZI cal A Enter gt You get this message Going to initialize file 7STAR Continue Y N Answer yes and the catalog will be cleared type ALL to verify that the catalog is now empty You can then mak new ntries following the instructions on User s Manual pp 25 28 Your entries do not have to be sequentially numbered 1 2 3 4 5 You could instead for xample nter science targets as 1 2 3 4 5 and enter some standard stars starting numbering them as 100 101 102 103 etc At the end of your run pleas delet th contents of 7CAT with the same command 7CA
32. ter opening or closing the slit disconnect the power cord and when you return to Computer Control Mode if the ONDOME command has been given then the dome will return to its normal position If there is no power to the outlet used to power the slit motor or the dome does not move despite having given the ONDOME command and having disconnected the power to the slit motor check the circuit breaker in the panel behind the door immediately to your right as you enter the dome The dome s circuit breaker is at the bottom of the panel three breakers connected together The circuit is closed if the breaker is clicked in all the way to the left If the breaker has been tripped it shifts towards the right somewhat If you are not sure whether th breaker has been tripped click it over all the way to the right then click it all the way over to the left the on position It should click audibly SECTION 9 OTHER USEFUL INFORMATION North Finder Scope field of view radius 30 0 5 and the cross hairs are each 7 5 in length 17
33. those coordinates hav been precessed to on the current date the Wanted field and can see what coordinates th telescop is actually pointed at the Actual field where Actual Wanted Offset There is also a line for Galactic Coordinates For the fields Offset Col and Dial however th values ar given in degrees minutes and seconds of arc This is done so that Offsets in RA and Dec are in the same units This obviates the need to mentally multiply the RA Offset Col and Dial values by 15 to turn hours minutes seconds of time into degrees minutes seconds of arc The values that you find in the fields Offset Dial and Col are determined by the previous user of the telescope The relations between Offset Dial and Col are discussed in detail below For now if the Dial and Col values are clos to those depicted in Figure 1 above then likely the pointing will not need much adjustment before you can start observing your first target The current values in the Offset field do not matter becaus they will be set to zero in the next step STEP 8 Make sure that the Secondary Mirror controller is set EO the collimate position and turned Of Turn on the Secondary Mirror Power Supply 24V Power Supply and the RA and Dec Power Amps the three units below the desk On the RA and Dec Power Amps make sure the Motor On switches are also switche

Here

Contents

Download Pdf Manuals

Related Search

Related Contents