IRAF script for COMICS imaging data reduction
The readout sequence of the COMICS detectors (320x240 pixels^2) implies
that the readout noise in each of 16 channels (20x240 pixels^2) should be
more or less identical. Therefore it should be possible to eliminate this
identical readout noise by subtracting the median of channels.
The raw image is shown on the left. The image on the right has been treated
with this noise reduction technique (sakomag.cl). In this case, the median
constrcuted from all 16 channels was subtracted from the raw image. It can
be seen that the stripy horizontal noise is effectively eliminated by this
The total integration time = Q_1FRAME * Q_CHCN (look them up in the FITS header)
where Q_1FRAME is the integration time per co-added frame
and Q_CHCN is the number of chop sequence (A + B beams).