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In arbitrary order...

Q: Taking a series of exposures with multrun, or using the -nruns parameter in a dither script, the exposure series hangs with or after the fourth exposure. No more images are being taken, and in the talker window I can see the following error message: 'insufficient space left in buffer'
A: Look up on which DAS machine LIRIS is running (e.g. DAS31). In the corresponding orange DAS window, do


In the other window where you issue the observing commands, do

  online LIRIS@whtdas31
  bias liris

Then check that the RTD is updated after a glance.
Q: I get a red alert window about the OCSCorbaDrama interface, pointing me to fault report 17037
A: In the observing window, do

  ps -Aef | grep OCSCor

which will say something like

  whtobs 23960 [....] tclsh /wht/release/bin/OCSCorbaDramaInterface

In that case,

  kill -9 23960
  OCSCorbaDramaInterface &

Q: The Real time display does not update the image anymore or is behaving erratically!
A: Check if you have switched the file detection on. If yes and the RTD does not update, close the RTD control window and the DS9 display. Then, from the system console, restart the RTD with

  startudasrtd &

Then check that the RTD is updated after a couple of glances.
Q: The LIRIS mechanisms GUI disappeared!
A: Restart it with

  start_liris_inf &

Q: LIRIS temperature and pressure window has disappeared. This window also has the LIRIS arc lamps on/off buttons.
A: If you are sure you do not have it, you can restart it with

   starttempgui &

Q: The multrun series in a mdither script stops after the 4th exposure, and I get an 'insufficient space left in buffer' error message in the talker window.
A: Do a shutdownobssys in the yellow DAS31 window, followed by an obssys and a startobssys. Possibly, do a shutdownobssys and a startobssys in the system console as well.
Q: The sky lines / slit image in spectroscopy are significantly tilted (or any other filter wheel did not move fully in place)!
A: Likely, the corresponding wheel lost its position. Do

  lsethome <slit | fwheel1 | wheel2 | grism | pupil | all>

then try again. You need to bring LIRIS back into imaging mode after this to be able to continue.
Q: I get a red error message in the black camera server window (Fig. \ref{liris_server}) for LIRIS, and I can not take any images more!
A: You have lost connection to LIRIS. Do a startobssys in the yellow DAS31 console. In any case, ask the OSA or OSS for assistance.
Q: The LIRIS images show very strange features, or a negative imprint of previous images, in particular in dark frames. It does not go away even after hours!
A: That can happen. You can fix this with a dasreset in the yellow DAS31 (can change into DASxx) console. In any case, ask the OSA or OSS for assistance.

Q: I just can't get this object on the long slit, it is always slightly off after using the lobject_inslit command. Or I get it on the slit, but once I take the spectrum, the source has wandered off the slit.
A: Use the autoguider! And give the autoguider 30 seconds after the command has finished to settle down, then take another image. The seeing might also fool you and drive the source around. In that case, increase the exposure time. Even if you do not use the autoguider, wait for at least 10 seconds before the next image to make sure the telescope has settled into its final position.
Q: I have centred the object on the slit, but I do not see any spectrum.
A: Switch back to imaging mode. Be autoguiding. Re-acquire the object. Take a through-slit exposure by moving in only the slit wheel ( lslit <slit name>). Can you see the object now in the slit? If it is well centred, then continue.
Overplot the corresponding slit mask over the through-slit exposure. Are they properly aligned? If not, do a lsethome slit, then limage <filter> and start over again.
Q: I got an alarm that the temperature / pressure of LIRIS is out of limits!
A: Inform the OSA. Likely, one of the temperature or pressure sensors has just failed. The OSA can switch to a spare sensor. Or, LIRIS ran out of nitrogen (unlikely, though), in which case the OSA can refill the cryostat. Pressure and temperature alarms should always be followed up and clarified the OSA before you can continue observing.
Q: I don't get any light through LIRIS, or I observe a strange vignetting (shadowing) in the detector edges.
A: Check that the Acq/Comp mirror is moved out of the light path, and that you didn't forget to move out the neutral density filter after e.g. taking spectroscopic flats.
Q: I accidentally killed the observing log window, how do I get it back?
A: In pink window (with the prompt SYS>) type obslog &
Q: Using imaging polarimetry, I get the dead row on top of one of the beams, how to put it in between the 2 middle beams?
A: This might occur with high airmass. Put any other slit in and after that go back to clear0p25 slit. Skyflats are taken with high airmass, to avoid this problem one could put the correct imaging polarimetry setup already before moving to skyflat position.
Q: What to do if the LIRIS calibration lamps (Argon and Xenon) won't turn on?
A: Ask OSA to reboot the portserver. It is found next to LIRIS behind the door that has a huge IAC sticker.

Q: How to recover the CCD Status window?
A: First make sure it really is not only minimized. If you are sure that the CCD Status window is not there type in pink WHTICS window:
SYS@taurus> mimic -mimic "SUMMARY ' + $instruments + '" -title "CCD Status" -size "873x531-28+3" &

Q: If there is a problem with the LIRIS temperature - SetPoint Temp. is 0K
Possible solution is to type in the pink WHTICS window:
SYS@taurus> ltempcntroff
This will turn the Control loop off.
SYS@taurus> ltempsetp
This will turn it back on.

Q: How to open the arc lamps window?
A: If you are sure it is really missing then type in the pink window:
SYS@taurus> lampsgui &

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Contact:  (LIRIS Instrument Specialist)
Last modified: 02 June 2017