Instruments & Operations

 

 

Issues that LBC Observers Should Know About

Firefox and the LBC User Interface

  1. Restart Firefox each day: The observer workstations, obs2, obs3 and obs4, have a propensity to become very slow so that window and cursor management become impossible. The apparent cause is heavy memory use by Firefox causing swapping. Be careful about having Firefox using more than 20% of physical memory. See Issue #806 for details. We've set the sdtobs Firefox profiles to Clear Private Data (under Preferences - Privacy) each time Firefox is closed. To do the same for your account, Edit Preferences to check the box to "Always Clear my private data when I close Firefox". If you close all your Firefox windows and restart Firefox once a day, everything should be happy. Note that killing Firefox can be done at anytime without interrupting observations. Note also that you must kill all of your Firefox windows, not just the one with the LBC UI.
  2. Firefox already running but not responding: Occasionally when you try to start a firefox session, you get the error "Firefox is already running, but is not responding..." This happens when there is a lock file that has not been deleted. To find this file, type: 'find ~/.mozilla -type f -name '.parentlock' -ls. This will generate a list of files called '.parentlock' with the dates/times that they were created. Delete the most recent one.
  3. Turnoff Protocol: Normal protocol would be turn off the LBC camera(s) at the end of the night, and turn them on again in late afternoon. Leave housekeeping power on all the time. Be sure to turn the cameras off (including housekeeping) if thunderstorms threaten. However, it seems that the system is more stable and reliable if the cameras are left on 24 hours a day - this is acceptable practice in good weather. The serial protocol of the housekeeping telemetry seems to get confused if it is on continuously for several days. So if the camera hasn't been turned off for some other reason, you may need to cycle housekeeping off/on to restore the temperature and vacuum values.
  4. Automatic restart after crash LBC has a new feature so that if the "lbc" server program crashes, it automatically restarts and returns to the previous power state of the camera. This feature is your friend and makes restarting the camera significantly easier and faster, but it can also bite you if the program crashes in an unusual power state (it tries to return to that unusual state). (Delete the power.conf file on the CMU if you need to cancel the remembered state.)
  5. Soft hangs of UI: There are still some soft hangs of the LBC UI that often cure themselves (and rarely last more than 6 seconds). Multiple LBC Control windows are now permitted, but take care to issue commands from only one at a time. Try changing UI pages on your browser to free things up. (It appears that this is more of a Firefox problem than an LBC UI problem.)

Focus and collimation

  1. Filters for focus/collimation: Use V-BESSEL extrafocal for all Blue focussing, and use r-SLOAN extrafocal for all Red focussing. The OB called RB_rVfastextra.ob uses these two filters. Do not focus with extrafocal images from other filters, because they have uncalibrated spherochromatism.
  2. Apply Z11=+1000nm to SX at start of night: LBC-Blue and SX mirror presently start with about -1000 nm of Z11 from the default configuration. This makes the central hole in the extrafocal pupils hard to identify, and hinders LBCFPIA convergence. A good practice is to ask the telescope operator to apply Z11=+1000 spherical aberration correction to the SX mirror before the first extrafocal image of the night (or whenever Clear Active Optics has been done). (The operators are also trained to do this.)
  3. Feedback on mirror movements: The LBC UI doesn't provide any feedback about whether telescope and mirrors are on target. The TCS folks have added this information as a bonus feature on the new IIF GUI. To display this GUI, ssh to lbtmu01 and say "IIFGUI &".

OB Preparation

  1. Focus/Collimation on fields with extended objects or many non-stellar objects The pupil analysis routine does not give accurate results for non-stellar objects, such as HII regions or distant galaxies, even if they may look compact like stars. The standard focus and collimation OB, RB_rVfastextra.ob, does not command the telescope to move. You will need to create a custom RB_rVfastextra.ob with coordinates explicitly entered to point to a region that is offset from the extended or crowded field target. The interactive pointing feature in the OB GUI may be of help in choosing a suitable field.