Image Quality

Double Peaked Images

Symptom
Double peaked images.
Problem
Possibly due to Pupil Mask Rotator (PMR) not operating.
Solution
Check the NIRC2 status gui. If you are using one of the Hex patterns, and either tracking is false, or, the angle is fixed at 0.0, then likely the problem is due to misalignment of the hex mask. If tracking is false, start tracking with "pmrrot on". If tracking is true, but the angle is stuck at 0.0, restart the daemon with nirc2 start pmr.

Elongated Images

Symptom
Elongated images in off axis acquisitions. On axis acquisitions appear normal.
Problem
Rotator mode is not set to Position angle. This can happen if you realign the laser at zenith using ACAM after releasing NIRC2 for observing.
Solution
If the rotator position angle is set to stationary or vertical angle, we need to reset it. In a waikoko terminal, issue the command rotate 0 posang to set the rotator to 0 in position angle mode. Check that DCS inidcates the rotator is now in position angle mode. Acquire a test image to check image quality.

Chevron Noise Pattern

Symptom
Chevron noise pattern as seen in left hand side of the two images shown below (displayed with ds9 using histeq).

Problem
Possibly caused by the filter animatics motor (most likely motor 5, the outer filter wheel) staying in an energized state because it did not quite reach its destination. This seems to happen more frequently when selecting narrow band filters (e.g., Hcont, Kcont).
Solution
At a waikoko prompt, type user eng, followed by exxon. This moves the outer filter wheel 1 count relative to its current position, forcing it into a motor off state. A dark should look more like the nominal noise pattern that is shown on the right-hand side of the above ds9 figure.

Vignetted Image

Symptom
Vignetting over 1/3 of the array is apparent in wide camera images. Much lower vignetting may also be present in the narrow camera, but the narrow camera effects are difficult to detect.

Above: Wide camera flat image with vignetting present, and a diagonal cut across the image from upper left to lower right.

Problem
Slit aperture is partially in the beam.
Solution
Issue a sltclr in a waikoko window.

Crop Circle in Flat

Symptom
See a dark annulus that looks like a crop circle in a flat image like the one shown below.

Problem
The AO bench has not been configured for flats, and the AO hatch is closed.
Solution
At a waikoko prompt, type configAOforFlats to set up the bench.

Server Problems

Exposure times are negative numbers or cannot access alad keywords

Symptom
Cannot show or modify alad keywords and the exposure meter is showing negative numbers or there are negative numbers in a waikoko xterm where the exposure command was issued.
Problem
There is something wrong with the alad server. Probably due to less than 3 alad servers running.
Solution
Restart the alad server (as nirc2eng on waikoko)
  1. nirc2 stop alad
  2. Wait 5 seconds
  3. nirc2 start alad
  4. Check servers using ctx or testAll
If this fails because motor and IO daemons not running, restart all three (io,motor,alad) with nirc2 start deamons; but see below for possible need to re-home and reset cold head speeds. If the transputer check fails, see GH instructions on OA page for power sequencing. Another useful document for any problems with terminal servers, etc is the NIRC2 gotchas document. Also consult Alad Troubleshooting Tips & Tricks

Cannot show or modify motor keywords

Symptom
Cannot show or modify motor keywords (Unable to read NIRC2 THEAD2LO email alarm)
Problem
Likely due to power failure.
Solution
Restart the daemons and, if necessary reset cold speed and re-home motors.
  1. nirc2 start motors (starts both IO and motor daemons)
  2. Check motors with showmot (false values under home imply need to re-home)
  3. If motors are homed skip down to cold steps.
  4. Rehome the motors as follows:
    1. For all motors except camera and slit slides (i.e., FWI, FWO, GRS, SHR, PMR, PMS, PSI, PSO):
      1. mm xxxRESET=1
      2. mm xxxINIT=1
      3. mm xxxHOME=1
    2. For SLS, SLM and CAM, use the poshome command after the reset and init. Check homelog.070220 to be sure behavior is consistent. Try not to home SLM and SLS to negative limits (see RC for details). Update the log if big changes.
    3. Reset cold head speeds ( procedure)
  5. Some power failures have resulted in chiller-failure-and-then-CCR-off. If CCR off for approx. 2 hours or more, follow this procedure
  6. If the problem is specific to motor and io daemons (showmot and snaptemps hang); the problem may be with the emulex terminal server. Try telnet nirc2ts1. During troubleshooting 20aug2010 this connection attempt alone possibly resolved a comms problem with the io/motor daemons.
  7. A problem that has occurred about 8 times as of 01nov2010: Cannot show or modify keywords (or snaptemps or showmot). AND any new attempt to log into waikoko is very slow and takes about 5 minutes. Solution seems to be either wait it out (suspect some external NIS problem or other network service problem); or, reboot waikoko. To reboot waikoko follow: waikoko reboot procedure

Lakeshore Communication Problems

Symptom
Cannot read Lakeshore keywords (e.g., tempdet). First indication is often the email alarm: "Unable to read NIRC2 Lakeshore 340 keywords".
Problem
Serial communication occasionally locks up.
Solution
See procedure

Alad Server Crash

Symptoms
Exposures stall with information written to the terminal that indicate
Problem
The alad server has crashed.
Solution
  1. From the pulldown menu select NIRC2 Control → Server Subcomponents → Recover . Alternatively, execute the command recover from a NIRC2 control terminal.
  2. This will run recoverAlad.csh in an xterm.
  3. Answer Y at the prompt.
  4. Hit enter on the yellow terminal to end the xterm session.
  5. Kill STATUS gui and Quicklook software
  6. restart status gui, NIRC2 Control → Interface Subcomponents → NIRC2 Status Display
  7. restart image display gui, NIRC2 Control → Interface Subcomponents → Start QuickLook

The recover alad script will restart the alad server processes and restore the last known settings for the detector keywords. Verify that the new Status gui displays the last known detector parameters and that the data directory specified correctly.