Last Friday (Aug 9), we attempted to observe H and K spectra (in f/10) of nearby galaxies. While moving the galaxie's core across the slit, we noticed that the response in both quadrants between columns 129-256 is noticeably lower than in the other quadrants (columns 1-128), at the level that we could no longer see the sky-subtracted spectra of the galaxy at all. (When the galaxy was centered somehwere between columns 1-128, we could distinguish its spectra almost clearly.) We checked that the core of the galaxy was centered on the slit, that it wasn't cloudy, and that we were getting sky-lines. All of which checked out ok. Has anyone noticed this drop in the detector's response before? Could this be due to the instability of the bias level? Also, we got all worried about the saturation level at 4 in the morning. The soft-saturation level is quoted to be ~28,000 counts. In what format? Iraf or Fits? (The issue here is that the iraf images have a bias level of +8,000 counts, whereas the fits images that are *later* read with iraf, have bias levels of -2,000 counts.) APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 27 in the apo35-grim archive. You can find APO the archive on http://www.astro.princeton.edu/APO/apo35-grim/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-grim@astro.princeton.edu APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO