subsection -- Make a subsection readout CCD image
subsection subimage image
- Subsection image to be created.
- Full image from which to take the subsection readout.
- ncols = 82, nlines = 50
- Number of image columns and lines in the full subsection image including bias regions.
- CCD section of the subsection. This is the image section of the full image to be used.
- datasec = "[1:50,1:50]"
- Data section of the image.
- trimsec = ""
- Trim section for later processing.
- Prescan or overscan bias section.
- overwrite = no
- Overwrite an existing image? If no a new observation is not created. There is no warning message.
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 artobs ). This task is designed to be used with the ccdred 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 ccdsec 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 artobs.biasval with noise given by artobs.sigma .
Also the image image header parameters from the reference image are copied and the data, bias, trim, and ccd section parameters are updated.
1. To create some test CCD images first create full frame observations with the task artobs . 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