A simple test Camera.
Notes
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The camera has one ccd with name "0".
That CCD has four amplifiers with names "00", "01", "10", and "11".
The camera is modeled after a small portion of the LSST sim
Summer 2012 camera: a single detector with four amplifiers,
consisting of raft 2,2 sensor 0,0, half of channels 0,0 0,1 1,0 and 1,1
(the half closest to the Y centerline).
Note that the Summer 2012 camera has one very weird feature:
the bias region (rawHOverscanBbox) is actually a prescan
(it appears before the data pixels).
A raw image has the sky in the same orientation on all amplifier
subregions, so no amplifier subregions need their pixels to be flipped.
Standard keys are:
* ``amp``: amplifier number: one of 00, 01, 10, 11
* ``ccd``: ccd number: always 0
* ``visit``: exposure number; test data includes one exposure
with visit=1