• Image Quality
  • Double Peaked Images
  • Chevron Noise Pattern
  • Vignetted Image

• Server Problems
  • Exposure times are negative numbers or cannot access alad keywords
  • Cannot show or modify motor keywords
  • Lakeshore Communication Problems

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"

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 staying in an energized state because it did not quite reach its destination. This seems to happen more frequently when selecting narrow band filters.

Solution

Select brgamma ("filt brgamma"), select Kp ("filt Kp"), and take another dark. The result 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.

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 <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 a "ct" 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 proplems 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/cam, use the poshome command after the reset and init. Check homelog.070220 to be sure behavior is consistent. Try not to home SLM/SLS to negative limits (see RC for details). Update the log if big changes.
   3. Reset cold head speeds (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