Subject: Recent Hangs

From: annis@sdss.fnal.gov

Submitted: Fri, 12 Apr 96 13:03:14 -0500

Message number: 30 (previous: 29, next: 31 up: Index)

The DSC has been hanging up more frequently recently.

We believe that the DA is waiting for lines that the camera
said it would send, but never did. Typically these are the
last few lines on the image.

We have made a new version of DOP that handles this situation 
gracefully. It will time out after waiting 180 seconds, and write
what it has of the image to disk. It will tell the observer that
it is doing so.

Other changes we have made to DOP include:
	removal of beginSleepReadout: message 21 tells of the fix.
	addition of code that produces files required to push
		DSC data through the MT pipeline with a minimum
		of effort. This is likely to be of interest
		only to Fermilab and SDSS folk.

Also, we have made the DSC in staring mode take 100 lines of overscan
rows.  These turn out to invaluable for removing the sinusoidal
vertical banding. We (Michael Richmond, Brian Yanny, Steve Kent,
and I) have been exploring the best way to remove the bias.
Our best path so far has been to:
	a) median down the overscan rows, subtract this from the image
	b) average overcan and bias cols for a given row, subtract
		from that row, for all rows on the image.
	c) then explore super-bias combination images, darks...

Finally, we wish to remind users that stray light is a serious problem
with the DSC. Use the baffle! If you find that you cannot use
the baffle, point in the East, far away from the lights of
El Paso, Alamagordo, and the air force base.

Jim Annis
	

APO APO APO APO APO  Apache Point Observatory 3.5m  APO APO APO
APO
APO  This is message 30 in the apo35-dsc archive. You can find
APO  the archive on http://astro.princeton.edu:82/apo35-dsc/INDEX.html
APO  To join/leave the list, send mail to apo35-request@astro.princeton.edu
APO  To post a message, mail it to apo35-dsc@astro.princeton.edu
APO
APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO