The 3.5 Meter at Apache Point Observatory

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Session 44 -- The Status of Large Telescope Projects, Instrumentation and Plans for Large Science Projectects in the Areas of Wide-Field Surveys
Oral presentation, Wednesday, June 14, 1995, 2:00pm - 5:30pm

[44.04] The 3.5 Meter at Apache Point Observatory

Donald G. York (University of Chicago)

As of November 1, 1994, the 3.5 meter telescope at Apache Point is in regular science operation. About 15\% of the time is still used for engineering. The performance is still being improved. At present, we achieve 4 arc second rms absolute pointing from 20 to 89 degrees above the horizon. Image sizes are one arc second on a regular basis. The best open loop tracking achieved is 0.1 arc sec. errors over 10 minutes, though it can be worse. Closed loop tracking is better than 0.1 arc seconds. No aberrations from the mirror supports have been detected. The honeycomb primary mirror is kept at ambient temperature during the night time. Temperature non-uniformities in the back and front plates are controlled to be the same to 0.1 degrees centigrade.

The telescope is regularly used with an infrared imager, a medium resolution spectrograph, and a large format, drift scan CCD camera. An echelle spectrograph, a high angular resolution camera, and an adaptive optics system are being integrated into the system. Instrument changes can be made in less than 20 minutes, at night. All instruments are operational and can be mounted by one person at any time. The observatory is operated by a full time staff of 6.6 individuals.

Remote operations are possible from all ARC campuses. Over 70\% of the observing is carried out this way, with site visits by astronomers only for mounting visitor instruments or for training purposes. Observing functions, including complete telescope control, instrument control, and data retrieval are carried out by the remote observer. The telescope is scheduled on an hourly basis, two months in advance of the actual runs. The individual university members of the project control their own time allocations and intra-institutional trades of time. The project partners are the University of Chicago, New Mexico State University, Princeton University, the University of Washington, and Washington State University.

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