DIS STATUS - 01 September, 1995 I. Chips II. Hardware III. Software IV. Documentation I. Chips Earlier this year the red chip bias level was sporadically jumping from it's usual value of ~4400 ADU up to ~6300 ADU. There have been no reports of this bias jump since June 23rd. During his June engineering visit, Richard Lucinio checked the circuit boards and touched up a few weak solder joints. The total mean bias level in the overscan regions of 85 recent images was 4336 ADU, the standard deviation was 40.4 ADU. None of the overscans had mean bias levels higher than 4357 ADU. Images taken with the blue chip still have a low level noise pattern. The pattern is roughly sawtooth with a total amplitude of 15 ADU, and repeats every 40 pixels along an axis tilted 36 degrees with respect to the y-axis of the chip. II. Hardware Richard Lucinio worked on the DIS hardware in early June of this year. Here is a brief summary of the DIS hardware problems he addressed. Turret - was not properly detenting and its motor was dropping steps. The action of the motor was modified to allow the turret to seat itself in the detent, and the turret assembly was balanced. Subsequent tests and observations indicate that the turret position is accurate and repeatable (within the expected limits of the design). Firmware was added to verify turret position before and after moves. This was done to reduce the chance of the turret moving to a different position than the one requested through the remote interface. Grating - The blue high resolution grating tilt was not very repeatable. Its tilt home switch was found to be loose. After tightening the switch the tilt repeatability improved dramatically. III. Software Brian Yanny and Bob Lowenstein have updated the MC and Remark software to enable users to readout an image early and save it to disk. We are still restarting the DIS ICC software each afternoon to avoid the occasional floating stack overflow that occurs after the software has been running for a long time. IV. Documentation The DIS users documentation was last updated on 1 June, 1995. There is a new WWW document, Remark - Frequently Asked Questions, that has some (hopefully) helpful information for observers who operate the DIS through the Remark interface. The URL is http://tycho.apo.nmsu.edu/site/remark.html -K. Gloria APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 4 in the apo35-dis archive. You can find APO the archive in /u/strauss/apo/mailer/apo35-dis on astro.princeton.edu APO To join/leave the list, send mail to apo35-request@astro.princeton.edu APO To post a message, mail it to apo35-dis@astro.princeton.edu APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO