7 September 2005 The on-chip guiding system of the wide-field infrared camera at CFHT
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Abstract
The Canada-France-Hawaii Telescope (CFHT) is commissioning a new Wide field Infrared Camera (WIRCam) that uses a mosaic of 4 HAWAII-2RG near-infrared detectors manufactured by Rockwell. At the heart of the instrument is an On-Chip Guiding System (OCGS) that exploits the unique parallel science/guide frame readout capability of the HAWAII-2RG detectors. A small subsample of each array is continuously read at a rate of 50 Hz while the integration of the science image is ongoing with the full arrays. Each of these guiding windows is centered on a star to provide an error signal for the telescope guiding. An Image Stabilizer Unit (ISU) (i.e. a tip-tilt silica plate), provides the corrections. A Proportional Integral Differential (PID) closed loop controls the ISU such that telescope tracking is corrected at a rate of 5 Hz. The guide window size and readout rate are adjustable but typical numbers are 8×8-16×16 boxes read at 50 or 1.5 Hz. This paper presents the technical architecture of the guiding system and performance measurements on the sky with WIRCam.
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Loic Albert, Martin Riopel, Douglas Teeple, Jeff Ward, Greg Barrick, "The on-chip guiding system of the wide-field infrared camera at CFHT", Proc. SPIE 5881, Infrared and Photoelectronic Imagers and Detector Devices, 58810A (7 September 2005); doi: 10.1117/12.617533; https://doi.org/10.1117/12.617533
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