I've updated the insformation for setting rotation angles on www.apo.nmsu.edu/Instruments/DIS/slitangle.html. I think you will find some helpful informationin there. Thanks to Bernadette Rodgers for prompting me to update this. - Karen G. APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 74 in the apo35-dis archive. You can find APO the archive on http://www.astro.princeton.edu/APO/apo35-dis/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-dis@astro.princeton.edu APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO