Heidi Newberg and I were talking about the 3.5-m today, and she mentioned an idea that sounded promising: why not purchase a second tertiary mirror? This "spare" could be cleaned/aluminized frequently and swapped with the other tertiary, so that a clear mirror was always on the telescope. If, for the sake of argument, the tertiary is currently reflecting 80% (or less) of the incident light, replacing it frequently with a mirror reflecting 90% of the incident light would yield an increase of > 10% in overall throughput, for all instruments. Michael Richmond APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 2 in the apo35-telescope archive. You can find APO the archive on http://astro.princeton.edu:82/apo35-telescope/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-telescope@astro.princeton.edu APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO