Please note that the new medium dispersion gratings for DIS are available *now*. It is not necessary to wait until 2Q1998 to use them. Since the scheduling request forms for the current quarter do not include grating requests, please notify the APO staff at least 24 hours in advance if you want to use the new gratings. To be on the safe side, it wouldn't hurt to notify them of your grating preferences, whatever they are. Note that you may have to lose observing time (all charged to your program, not shared with an adjacent DIS program) if your use of the new gratings requires a grating change during the night this quarter. We hope to avoid such middle of the night changes in subsequent quarters (be sure to use the new template, see apo35-general #254 for 2Q1998 and beyond). I reproduce below the info on DIS gratings given in apo35-general #237. Ed Turner +++ New medium dispersion gratings for DIS have arrived and will be tested in the next few months. Here's a summary of what will be available (these are approximate numbers only): Low resolution Blue Red Dispersion 6.2 A/pix 7.0 A/pix Wave range 3175 A 5600 A Medium resolution (new) Blue Red Dispersion 3.1 A/pix 3.5 A/pix Wave range 1590 A 2800 A High resolution Blue Red Dispersion 1.6 A/pix 1.1 A/pix Wave range 820 A 880 A The crossover wavelength is 5350 A. Note that the addition of the medium dispersion gratings is an enhancement, not a replacement, of current functions (some people have the incorrect impression that the low dispersion mode will not be available). While DIS handles only two pairs of gratings at once, it should be possible to specify the setup needed at the beginning of the night and have the proper gratings installed. APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 256 in the apo35-general archive. You can find APO the archive on http://www.astro.princeton.edu/APO/apo35-general/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-general@astro.princeton.edu APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO