This is an important note for GRIM observers; the orientation of the instrument has been changed! A mistake made many years ago and honored in the intervening years has been corrected, and the instrument will be 180 degrees from its previous orientation. The correction grants some benefits to the observing specialists, but unfortunately for observers the change will mostly be a nuisance. The information on the Orientation and Offset Direction web page at http://www.apo.nmsu.edu/Instruments/offsets.html is now correct for GRIM (information for other instruments may be out of date and will be checked soon). In f/5 configuration, North is now up on the chip, and East is to the left. If observers prefer the old North down/East right configuration, they can slew with a rotation of 180 degrees in Remark. However, the directions of instrument offsets will still be as shown on the page: a +X offset from Remark or the MC moves the star to the right regardless of rotation, and a +Y offset moves the star down on the chip. This may affect the behavior of some dither scripts. If it is important to you to make sure that targets end up on a certain quadrant of the chip, or that dither offsets are made in a particular order, check the webpage and consult with the observing specialists to see if you need to make any changes to your script. Russet McMillan. APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 518 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