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Proceedings Paper

Megacam: paving the focal plane of the MMT with silicon
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Paper Abstract

Megacam is a 36 CCD mosaic camera that will cover a 24' X 24' field of view at the f/5 wide-field focus of the converted 6.5 m Multiple Mirror Telescope. The mosaic is a 9 X 4 array of thinned 2048 X 4068 pixel CCDs with 13.5 micrometer pixels. The CCDs are dual-output EEV devices in a custom package to allow the devices to be closely butted on all four sides. The dewar will be mounted to a 2 m diameter assembly that contains the filter wheels (for 30 X 30 cm filters) and the shutter. Telescope guiding will be accomplished with two additional CCDs mounted at the edges of the focal plane. The guider CCDs will be operated slightly defocused, one on either side of focus, to allow simultaneous focusing and guiding. Guide stars will be selected by reading out the full guider frame, after which only a small area surrounding the guide star will be read out. Our simulations show that the defocused guide star images will also be useful for low order wavefront sensing, allowing corrections to the telescope collimation. We are developing a new CCD controller capable of reading the full Megacam in 24 seconds. This controller will also be used to operate the guide chips.

Paper Details

Date Published: 9 July 1998
PDF: 10 pages
Proc. SPIE 3355, Optical Astronomical Instrumentation, (9 July 1998); doi: 10.1117/12.316779
Show Author Affiliations
Brian A. McLeod, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Tom M. Gauron, Harvard-Smithsonian Ctr. for Astrophysics (United States)
John C. Geary, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Mark P. Ordway, Harvard-Smithsonian Ctr. for Astrophysics (United States)
John B. Roll, Harvard-Smithsonian Ctr. for Astrophysics (United States)


Published in SPIE Proceedings Vol. 3355:
Optical Astronomical Instrumentation
Sandro D'Odorico, Editor(s)

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