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The Acquisition Cameras are optical CCD-based instruments within the Acquisition and Guidance (A&G) unit (module 1). Each Acquisition Camera provides two major capabilities: (1) telescope pointing verification via short exposures and fast readout of bright stars, and (2) target selection via intermediate-length exposures.
Retraction of the science fold mirror (used to direct the telescope, calibration or AO-corrected beam to a side-looking instrument), and insertion of the Acquisition Camera pick-off mirror allows a visible-wavelength image of the field to be taken.
The Acquisition Camera can double as a high-resolution wavefront sensor (HRWFS) to measure the shape of the primary mirror), by insertion of a lenslet array in front of the detector.
Each Acquisition Camera has two filter wheels, one with bandwidth-limiting color filters and the other with neutral density filters. The detectors are TE-cooled, frame-transfer CCDs with 1Kx1K pixels covering a 2x2 arcmin2 field of view. There is no shutter.
The individual pixel size is 0.12 arcsec. The minimum exposure time is 0.006 seconds and the full frame readout time is 1.7 seconds.
The Acquisition Cameras have been offered for science use in the past. For completeness, the old Acquisition Camera pages are still available although no longer maintained.