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Proceedings Paper

CFHT MegaPrime guide and focus control system
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Paper Abstract

The Canada-France-Hawaii Telescope is now operating a wide-field visible camera with a one-degree field of view. We have developed a guiding and auto-focus system that uses two stage-mounted CCD cameras fed by Shack-Hartmann optics providing position and focus error signals to the telescope guiding and focus control systems. The two camera stages patrol guide fields separated by more than a degree, one to the north and one to the south of the main camera field. Guiding generates a 50 Hz correction signal applied to a tip-tilt plate in the light path and a low frequency correction signal sent to control telescope position. During guiding a focus error signal is used to adjust telescope focus. Calibration issues include guide camera focusing, image distortion produced by the wide field corrector, guide stage positioning, and determining ideal guide star positions on the cameras. This paper describes the resulting system, including preselected guide star acquisition, guiding, telescope focus control, and calibration.

Paper Details

Date Published: 15 September 2004
PDF: 10 pages
Proc. SPIE 5496, Advanced Software, Control, and Communication Systems for Astronomy, (15 September 2004); doi: 10.1117/12.550583
Show Author Affiliations
James N. Thomas, Canada-France-Hawaii Telescope Corp. (United States)
Gregory Barrick, Canada-France-Hawaii Telescope Corp. (United States)
William Cruise, Canada-France-Hawaii Telescope Corp. (United States)
Tom Vermeulen, Canada-France-Hawaii Telescope Corp. (United States)

Published in SPIE Proceedings Vol. 5496:
Advanced Software, Control, and Communication Systems for Astronomy
Hilton Lewis; Gianni Raffi, Editor(s)

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