DSC users: My understanding is that the data that both Kris and Xiaohui took for their efficiency calculations were taken after the camera was brought to FNAL for repairs. One of the reasons for the trip was that somehow water (or something) had condensed onto the chip, producing what looked like a mottled flat field. The anti-reflection coating is very fragile, and there were some photos taken at FNAL that clearly show damage to the coating. I suspect the QE has been seriously degrated. Jim Annis and Shu-i Wang brought the chip to SITe for cleaning, but the spots are still there. Did anyone do similiar calculations when DSC first got its current chip? --Connie Rockosi APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 26 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