Care and Feeding of the 1.2m (48") Telescope

Table Of Contents

Click below on the section you wish to read, or scroll down

• Introduction
• Startup
• Shutdown
• Misc
• Flats
• POINTING LIMITS
• Remote Observing
• Problems

Introduction

There are two secondary mirrors, each giving the same Cassegrain focal ratio, but one being undersized for IR observations (in recent years, we have not used the IR secondary). The secondaries are centrally supported and defined. The secondary mechanism (HEXAPOD) allows full remote control of the position of the mirror for collimation; however, observers can only use the focus movement.

The fork mount uses direct-friction drives, allowing very fast slewing (about 2 deg/sec) but with the potentially dangerous feature that the telescope can be moved manually when the motors are not engaged. The drive motors are controlled with a PC (the "mount PC") running software supplied by Comsoft. The dome position is encoded, and when properly set will follow the motion of the telescope accurately.

A guide system running on a Linux PC allows movement of the guide pickoff mirror, in the "topbox", focus of the guide camera, as well as autoguiding. The guide field is about 2x1.5 arcmin. The power for the guide camera should be left on. You will find the electronics box and its switch mounted on the mirror cell. Make sure the guider system is working first. See directions and operating instructions here: guide system . Instructions to operate the guider via the TCS program are available here.

The topbox also has an 8-position filter wheel, controlled by the guide computer, with an interface showing in the TCS program. Moving by 1 filter takes about 5 seconds, by 2 (3), 10 (15) seconds. TCS optimizes the filter wheel rotation, so no filter move takes more than 15 seconds. The maximum filter size is 4" ; inserts allow 2" square and round filters to be used (vignetting may compromise your observations with 2" filters). Observers are not allowed to change filters; please ask the staff during daytime if you need to change filters.

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Startup

Cold Start

The telescope is occasionally unplugged for safety reasons, during thunderstorms or while electrical work is being done. To start up in this case:
• (A) Make sure the telescope is zenith-pointing. The new method utilizes the "Ref Tele" entry in the ntcs GUI (see the tcs guide), or the "tele ref" command in telshell. The command references the telescope to 2 sensors and sets it and the coordinates to zenith. It is operational as of Sept 2009. The old (now backup) method was to check the levels on the North and East sides of the topbox, and move the telescope with the hand paddle if the drives are on and enabled, or if the drives are off, by pushing and pulling manually (fairly easy).
• (B) If unplugged, plug the two line cords (behind PC box) into the orange electrical outlets. One is labeled 48" Rack, the other Mount computer.

Warm Start

• (A) Make sure that the silver Drive Enable switch on the in the control room is down (disable).
• (B) The rack Main Power should be on at all times. If in some unusual occurrence the rack is off, turn on the rack Main Power. If it was off, there is a potential for a runaway when the motors are enabled. See Item D below about flashing RA and DEC
• (C) If the Realtime System is running on flwo48, type exit in the Telshell command window. Turn the TCS monitor on, and push the power button on the mount PC to boot up. Windows 98 will start up (do not play around with this computer!). Double-click on the TCS icon (little radio telescope) to start the PC-TCS program. Now click at the bottom of the screen on Startup TCS to bring up the TCS screen. Finally, hit the space bar to satisfy the program's needs for such things.
• (D) Check the mount PC monitor to see if PANIC is flashing or if the RA or Dec labels are flashing red. If yes, press F10, then F9, and then F10 again. The coordinate labels (RA & Dec) should turn from red to blue and steady. This happens occasionally when the rack has been turned off, or for idiopathic reasons.
• (E) Push the silver Drive Enable button up (enable) on the rack, after verifying that the Dewar is not connected to Keplercam.
• (F) To open the dome slit, type opensesame in Telshell. You might type instead "openall" to open both the slit and the mirror covers.
  If "opensesame" or "openall" fail, you may need to open the dome slit manually, and report the fault to the staff. Before starting the system, in the chamber, open the dome with the toggle switches (labeled) in the gray dome slit control box (also labeled) at the base of the dome, to the left of the slit. There are two switches, (1) a 2-position toggle to switch between manual and computer mode, and (2) a 3-position toggle to swich between neutral, open and close. First, align the box with the tall yellow ladder by rotating the dome with the handpaddle (in Telshell, you would send the dome to azimuth 45 deg). Next, climb the ladder and flip switch (1) from computer to manual. Then, flip switch (2) to open. Once the slit is open, flip switch (2) back to neutral, and switch (1) to computer. Closing is performed by setting switch (2) to close in manual mode. You may interrupt the opening/closing by flipping (2) to neutral. Make sure to switch the control box back to computer mode once the slit is opened/closed.
• (G) There is an air conditioner (A/C) in the chamber that is intended to keep the air inside the dome cool in daytime, but should be turned off during observations. The goal is to match the chamber and outside air temperatures at the beginning of each night. A/C thermostat settings vary significantly with the seasons. The observer should look at and possibly change the settings at the switch in the chamber as early as possible at the start of a run. The setting in degrees Celsius should be the temperature in the chamber at the beginning of the previous night, but it should not be set below 12C (the minimum operating temperature of the A/C). We maintain the temperature of the primary mirror near the ambient temperature in the chamber. We have an FTS chiller system that does the job very well. See the temps link for an example. The chiller system is off limits to observers. It must run at all times, so the heat-exchange fans in the cell must never be turned off. Make sure the switch for the fans in the rack is always in the ON position.
• (H) The guide camera electronics should be on at all times. If you find it off, turn the gain (next to the guide guider monitor) down about 1 full turn, then turn on the electronics power. Turn on the guide monitor if off.
• (I) Once the dome slit is open, open the mirror covers by typing "tele coversup" in Telshell. The command runs only at zenith. If not at zenith, a very red warning window will flash on your screen and the command will not run!
The switch on the rack that was used to open the covers in the old days must always be left in the close position.
• (J) Make sure the guide PC is booted up (see guider manual), which also contains reboot instruction.


• (K) On flwo48 (Linux PC), start the Realtime system by typing gokep (see, e.g., the Keplercam primer for details.) The telescope tracking and the dome tracking should be off when the TCS window pops up. Toggle the telescope tracking and dome tracking on using the Tele Tasks Menu. For Keplercam (default binning is 2x2) select on-chip binning ("small" = 2x2, "large" = no binning).


• (L) The most straightforward method is to use the "Ref Tele" entry in the ntcs GUI (see the tcs guide), or the "tele ref" command in telshell. The command references the telescope to 2 sensors and sets it and the coordinates to zenith. To double-check the positioning, acquire a bright star and check the coordinates. In the "New Coords" menu of the TCS you can load a bright star by selecting it with the mouse. After doing so, click on the "Slew Enable" button of the TCS, and the telescope will move to the star. Move the guide probe on-axis by clicking the "On/Off Axis" button in the TCS window. (The TCS manual and guider section have more details). If the star is visible, center it on the guide screen with the handpaddle (or on the CCD, by taking an exposure), and reset the telescope coordinates from the TCS window on flwo48, under the Tele Tasks Menu, with the "Set TelePos" command. (See TCS help under "Tele Tasks".)

Observers who want the telescope coordinates centered on one of the Keplercam amplifiers, rather than on the center of the chip, must take the following extra steps. After zeroing a bright star on axis near zenith (with the guider or by taking short exposures), use the "Set TelePos" from the TCS window. Make sure the coordinates shown are those of your star. Once you've verified the coordinates, from the TCS Tele Tasks menu, select "Amp Center" and pick an amp; see the TCS offset entry for more details.

If you don't see the star, with the guider on-axis, first consider the possibility that the previous observer zeroed the telescope away from the center of the array. Try reversing the popular offsets to amp 2, i.e., manually offset by +345, +345 and see if the star appears in the guider.
If the coordinates are way off and you can't find any stars in the guider view even after entering the offsets above, you should start by going to zenith. Stow the telescope from the Tele Tasks menu and type "exit" in the command window to exit the system. Then, go into the chamber, verify you are near zenith by eye, and use the bubble levels on the North (start with this one to set RA first) and East sides of the topbox. Move the telescope with the hand paddle if the drives are enabled, or if the drives are disabled, by pushing and pulling manually until each bubble is centered in its level.

Once you have achieved Nirvana, go back to the control room and if enabled, disable the telescope drives on the rack. Next, exit TCS on the mount PC using the menu bar at the bottom of the screen. Select and click on the manual exit option (or hit the appropriate key) at the extreme right-hand side of the menu bar. You will be offered a window with options; hit ESC 3 times and then RETURN, which will finally shut down TCS. Restart TCS on the mount PC by double-clicking on its icon (in the middle of the monitor), then click once on the TCS menu that appears at the bottom of the screen, then hit RETURN once you get a blue window. At that point, you can enable the drives again, restart the system with gokep on flwo48, enable tele and dome tracking, and proceed with your observations. Make sure to re-check the pointing by going to a bright star as described above.

If you have gone through all the steps above, you are ready to focus the telescope (see the Keplercam primer, Telescope Focusing).

You should be set to observe.

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Shutdown

• (A) From the Tele Tasks Menu, select Stow Tele. This will turn off the tracking, move the telescope to zenith and stow the dome.
• (B) DO NOT Shut off the Main Power switch on the rack. Doing this may cause motions to "Stack up" in tcs, and result in a runaway...
• (C) Shut off ("down" position) the silver Enable/Disable drive power switch.
• (D) Next stow the telescope and type "shutall" in Telshell to close the covers and the dome slit.
• (E) If desired, exit the system by typing "bye" in Telshell.
• (F) Fill the Keplercam dewar and enter an online fill log (on the main page).

Miscellaneous

There is a large two-speed fan that can be turned on after the dome is opened at night (to the South of the telescope).

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Flats

Please see the Telshell page for a description of command Ldomes. Type "dtime" in any xterm to find out the latest time you should normally start dome flats.
The steps that Ldomes follows are listed here.

If the counts are too low, the dome may be misaligned (view the dome webcam after command lightdome, if misaligned home the dome and try again); the flat lamps may not be working (with the chamber dark, turn on the lamps, view with the dome webcam after command lightdome, if not on call for help); or the CCD may have a problem (restart it using these instructions and try again).

Please see the Telshell page for a description of command Rskyflats. Type "ftime" in any xterm to find out when sky flats should be started.
Remember that sky flats are indispensable for u, as the lamp output is insufficient in that band.

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 Remote Observing

A: General Info

1.  Remote observing is intended for observers at CfA in Cambridge. It may be feasible from other institutions or from your home with a high-speed internet connection through your account at CfA. However, the additional network layers and possible barriers may slow you down and preclude observations. You should use the VNC viewer system for observations (also available for windows or Mac OS, see the instructions here). VNC is required, because a loss of connectivity at your location will not bring down the telescope control system. If the outage is temporary, you should be able to recover, or you may need to request a telescope shutdown from the 1.5m observer. It is still possible to observe by logging in with ssh (see below), but we strongly discourage it.
2. Note: if you require filters that will not be mounted for the run immediately preceding yours, you should provide a list of your filters via email to the staff (WP or TG) a few days before your run.
3.  If you need dome flats, see the description above.
4. Please coordinate with your remote helper.  He or she should have your  phone number, email address, remote host name, and any special instructions. It's a good idea to check by phone before starting up, to ensure that no one else is using the system. Make sure that you arrange for both opening up the dome and shutting it down. Take special care when neither Perry Berlind nor Mike Calkins is observing at the 1.5m to plan your night with the observer.
5. Don't always expect your 1.5m remote helpers to drop everything and help you immediately.  They are working as well, and will help you as soon as feasible.
6. Note that if your remote helper decides that weather conditions necessitate closing the domes, he or she may need to make the decision for the 1.2m without previous warning to you.
7. Please realize remote observing can be negatively affected by problems with the internet between Mt. Hopkins and your location that are beyond our control.
8. If there is a miscommunication and your remote helper is not at the 1.5m when you shut down at the end of the night, point the 1.2m West, away from the sun, at about 45 deg elevation. Weekdays, the day crew will arrive at about 9am MST. Notify them by email that the 1.2m remained open. On weekends, call the dorm room or the gamma-ray building in case someone is there that could assist. If that fails, call WP or EF.

 B: Starting Up

1. It is critical to have a dry run of remote observing procedures at the machine that you plan to use. We recommend trying it out during daytime (after calling in), so you'll be able to ask the staff questions if necessary.
2. Log into your computer in Cambridge.    You will be using vncviewer to access the system from flwo48, and perhaps also to access the guide camera. Make sure you are using TightVNC. If it is not available on your machine, you can find an executable at ~ted/bin/vncviewer. TightVNC is strongly preferred over the default RealVNC system at the CF. See the instructions for remote VNC use.
3. If the vncserver is not running, ssh into flwo48 using the observer account. (only observer can be used to observe with Keplercam).  Issue the command govnc to start the vncserver. Once you have connected to the server issue the command gokep to start the system inside the vncserver
4. Turn on tracking and dome tracking (under Tele Tasks Menu).
5. If your exposures are longer than 5 minutes, you will need to guide. To view your guide stars in the guider window, start the guider programs in another VNC window.
6. The pinkish guider Rgain button (below the slider) on the yellow ntcs GUI controls the camera gain. You must click this button to turn remote gain control ON (OFF when done). It is less immediately responsive than the local knob control. If the gain is too high you saturate the guide camera, so move it up slowly. Note: the local knob control should be turned to its minimum (CCW) to use the remote controls. Although it has an automatic gain control (AGC) that is supposed to prevent damage, be careful not to expose the guide camera to bright lights as much as possible. It is a very sensitive intensified camera, also very expensive.
7. If the gain does not seem to have an effect, ask the 1.5m remote observer to verify that the 1.2m guide camera is on (it should remain on at all times) or turn it on for you. Also, have her check the mirror covers!

 C: Acquiring Data

1. Please check the online documentation.
2. Use of catalogs is strongly encouraged.
3. The remote helper should check pointing off-line before turning over the system to you (at which point he should log out of the Realtime system).  Make sure to tell him/her whether you want the telescope centered at the center of Keplercam, or rather one of the individual amplifiers. Please refer to the manuals for instructions on centering on an amplifier. After that, first you open the Misc Menu on tcs, turn on dome track and tele track.  The catalog brightGaia.mct is an update of the older brightstars.mct with more recent star positions down to g=6mag.  Verify the pointing by moving to a bright star.  Adjust the guide camera focus.
4. Try using the new command kfindfwhm. 
   If you are set in the old ways, go to a fairly dense stellar field, and focus the telescope with nfoc or testfoc. See, e.g., the Keplercam primer.
5. Go to your first object, take an exposure, ftp it back to you machine, and use iraf and/or saoimage to view the data.  You can also do these remotely,  but the impact of the link may be painful.
6. The dome may close automatically if rain/high humidity occur.

 D: Shutting down

1. When you are done, stow the telescope, and call your helper to close as soon as she is able. If you were using remote gain please lower the gain to about 40, but leave it on.
2. Type "bye" in the telshell window to exit the telescope control system.

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Problems

• Reaching pointing limits
• Lost dome
• Lost filter wheel/pickoff mirror
• Mirror covers fail to open/close completely
• Unresponsive CCD
• Blank CCD exposures
• Unresponsive tcs (on flwo48)
• Confused account (on flwo48) (software problem)
• Unresponsive monitor (on flwo48)
• Unresponsive flwo48 ***CAUTION***
• Mountain power outage

• The software has a protection against slewing too far over. The telescope will not move if you have requested an illegal move. On the mount PC monitor, the word Next will be highlighted in red. It is possible however, to go to the limit by slewing with the hand paddle or by tracking if the initial pointing did not violate a limit.

  The pointing limits (set in TCS on the mount PC) are: |HA| <= 5 hours, -30 < DEC <= +89 degrees, sec(Z) <= 5.0 and elevation >= 29 degrees, as shown here.
  Rob has a somewhat tighter limit, |HA|<= 4:15 hours (as of 12/29/16), for safety. We can relax this limit (and the DEC, EL and sec(Z) limits) somewhat if you need to work slightly beyond these values. Please request that the limits be changed in advance of your observations, describe the circumstances, and the the limits you need.

  There are several possible ways to reach a limit. One is by moving there with the hand paddle. Another is by having the telescope track into the western limit. If the telescope goes to a limit, the motors shut off automatically. The dome may also rotate incessantly. To restart, first and most important, find out what caused the problem. One possibility is that Rob observed a long transit and kept tracking to the West, in which case it shoud raise an error flag for the 1.5m observer.

  In the control room, disable the telescope drives. Once you know what went wrong, go out to the telescope and determine whether a move in RA or in Dec is needed. If an RA move is needed, push on the fork (rather difficult) for a few inches of motion. If a Dec move is needed, gently push on the top ring in an upwards direction for about a foot of motion. Now clear the "Panic" mode on the mount PC screen by typing "F9 F10 F9" (perhaps several times) on its keyboard. The dome should stop moving at this point after it has homed itself. Once both the "Panic" message and the "Disabled" messages are gone, you may turn on the drive enable switch.

  The telescope may now be moved with the hand paddle or under computer control (please don't repeat the previous move). You should check the dome to make sure it is homed; if not, use the home dome button in the TCS window (on flwo48), under "Tele Tasks."

 
 

• The dome occasionally gets lost. To retrieve the pointing of the dome, go to the Tele Tasks menu of the TCS and turn off the dome tracking, and then click on Home Dome. This will send the dome to its home sensor. Now turn the dome tracking back on.

 
 

• If the filter wheel and/or the pickoff mirror stop responding, or on startup the sytem hangs and fails to produce the TCS window, you should cycle the power to the topbox. First exit TCS (type "bye" in the telshell window). Second, go into the chamber and turn off the topbox power switch, on the SE side of the mirror cell. Turn it back on after a few seconds. Third, reboot the guide PC, (see guider manual), for restart info. Finally, restart the system and TCS, by typing "gokep" for Keplercam, and after a few more minutes, you will be back in action. If you are unsure about any of these steps, please call a staff member.

 
 

• If the mirror covers fail to open or close completely (e.g. 1 petal sticks), please call a staff member for guidance.

 
 

• If the Keplercam CCD stops or readout is much slower than usual, or you see a read error message in the TCS window, or the data are obviously distorted, you should restart the Keplercam CCD system as described here. Next, take a bias to see if the CCD is performing correctly. If that still fails, you should first exit TCS (see Lost filter wheel above), repeat the CCD system cycling procedure, and restart TCS as above. If you are unsure about any of these steps or the recovery fails, please call a staff member.

   
   

• If your exposures look like biases and you or the 1.5m observer confirm that the telescope is looking at an open slit and not at solid clouds or closed mirror covers, the shutter may not be functioning properly. Take a short exposure and listen (or ask the 1.5m observer to listen) for the shutter opening and closing on the chamber intercom. If there is no "clacking" sound, cycle its power at the gray box on the N-NE side of the cell and take another short exposure. If you are unsure about any of these steps or if the shutter still fails, please call a staff member for help. You may also need to

 
 

• Sometimes tcs freezes; everything else seems alive, but tcs won't work. A likely explanation is that there is a sub-window (like Focus or TeleTasks) hidden but still active. Try hitting the "front" key a few times or iconifying the main tcs window to make sure there isn't one of these hanging around. Another possibility is clicking "Begin Guide" when the guide camera power is off, if this is the case it will unfreeze when you turn it on!

  Check to see if the "rguide" window is still on the guider screen. If it's gone, you should restart "rguide" as described here. Your next step is to stop and restart tcs as described next.

  If your command window is still responsive, type exit there. When all the tcs-related windows are gone, type gokep to restart tcs.

  If that doesn't work, you need to stop tcs manually and start over. In any xterm other than the command window, type killcom. You should see the command window and all tcs-related windows disappear within a few seconds. You are then ready to restart by typing gokep.

  If none of the above works, it's probably necessary to reboot flwo48 and start over. If you do that, you might as well go through the whole telescope startup routine again.

   
   

• The flwo48 monitors turn their displays off after about 10 minutes of inactivity. Usually, you bring them back on by mousing around. However, it may happen that the right-hand display remains off, even after vigorous mousing. The cure is simply to press the monitor's on/off switch off and back on. A few seconds after such cycling, the display should come back on. If there is a deeper problem with flwo48 (which might mean that the left-hand display is frozen or remains off), you should reboot flwo48 (see below).

   
   

• Although it is unlikely, flwo48 may need to be rebooted during your run. An improper shutdown (e.g., by a power loss accompanied by a UPS failure, or by cycling the power without rebooting or shutting down from the OS) may result in loss of observing time. Currently, the proper way to shut down is from the login window at the displays in the control room. The reboot will take a few minutes. If you are uncertain about taking this step, please consult with staff. If there is a problem during the reboot, the machine may actually need root intervention, at which time you most definitely will need assistance.

   
   

• If you find your xterm windows on flwo48 are frozen or otherwise unresponsive and nothing you try seems to work, you may need to restore the observer (for Keplercam) account to a known working state. To restore the observer account to such a state, enter the command restore.obs (currently deactivated) in an xterm window (ONLY in extreme cases; please consult with staff before doing this).

 
 

• Our commercial power from UES (Unisource Energy Services) has been known to fail. Normally, the ridge generator kicks in quickly and delicate equipment survives thanks to UPS power. Occasionally, multiple failures may occur.
  Start by asking for help from the remote observer at the 1.5m, but also phone the staff if you have any doubts, and contact the MMT.

  If you are certain that the power failure caused the generator (at the ridge, for the whole mountain) to kick in, please notify our electrician, Tom Welsh, as soon as possible day or night (see the FLWO directory for his phone number). You can easily hear the generator at the ridge when it's running. Check for its sound if the power has gone off; emergency lights should come on. The normal sequence is for the UPS to go on, so power is maintained until the generator starts, in less than one minute. The emergency lights should then go off. If there is a power failure and the generator fails to start after a few minutes, you should shut down as much equipment as possible, as quickly as possible. Communications equipment has additional power backup, but eventually phones and radios may stop operating. Although phones may not ring, you may still be able to call out for some time.

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