.help subsection Oct87 noao.imred.ccdred.ccdtest
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NAME
subsection -- Make a subsection readout CCD image
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USAGE
subsection subimage image
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PARAMETERS
.ls subimage
Subsection image to be created.
.le
.ls image
Full image from which to take the subsection readout.
.le
.ls ncols = 82, nlines = 50
Number of image columns and lines in the full subsection image including
bias regions.
.le
.ls ccdsec="[26:75,26:75]"
CCD section of the subsection.  This is the image section of the full
image to be used.
.le
.ls datasec = "[1:50,1:50]"
Data section of the image.
.le
.ls trimsec = ""
Trim section for later processing.
.le
.ls biassec="[51:82,1:50]"
Prescan or overscan bias section.
.le
.ls overwrite = no
Overwrite an existing image?  If no a new observation is not created.
There is no warning message.
.le
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DESCRIPTION
This script task generates artificial CCD subsection observations
which include bad pixels, bias and zero levels, dark counts, flat
field response variations and sky brightness levels.  It creates an
subsection image which includes a bias section from a previously
created image (created by the task \fBartobs\fR).  This task is
designed to be used with the \fBccdred\fR package and includes
appropriate image header information.

First the task checks whether the requested image exists.  If it does
exist and the overwrite flag is no then a new observations is not created.
If the overwrite flag is set then the old image is deleted and a new
observation is created.

The image section give by the parameter \fIccdsec\fR of the reference
image is copied to the new image.  It is assumed the reference image
contains any desired zero level, bias, flat field, and dark count
effects.  The bias section is then added with a bias value given by
\fBartobs.biasval\fR with noise given by \fBartobs.sigma\fR.

Also the image header parameters from the reference image are
copied and the data, bias, trim, and ccd section parameters are
updated.
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EXAMPLES
1. To create some test CCD images first create full frame observations with
the task \fBartobs\fR.  Then set the subsection parameters
for the size of the subsection observation, the data section, trim section,
bias section, and the CCD section of the subsection observation.

	cl> artobs obj 5 object filter=V
	cl> subsection obj1 object
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SEE ALSO
mkimage, artobs, demo
.endhelp
