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The software now available is a package for doing relative calibrations of the
pixels, for averaging frames, and for cleaning images. Cleaning in this
context means removal of instrumental faults and other defects from the
images. A list of the relevant commands is provided for reference in the
section 
of this appendix.
The CCD--reduction involves the steps outlined below. Steps in paranthesis
[...] are optional but see the following discussion to determine if they are
optional in your particular case.
- [ Remove irrelevant columns of all frames ]
- [ Bias correct all frames ]
- compute an average DARK
DARK_AVG
- [ remove defects from DARK_AVG ]
- compute an average FLAT
FLAT_AVG
- dark subtraction
FLAT_AVG = FLAT_AVG - DARK_AVG
- [ remove defects from FLAT_AVG ]
- [ normalize the FLAT_AVG,( see Eq. ())
FLAT_NRM ]
- dark subtraction
SCIE_FRM = SCIE_FRM - DARK_AVG
- [ remove defects from SCIE_FRM ]
- flatfield the scie-frame SCIE_FLAT = SCIE_FRM/FLAT_NRM
- compute the average of science frames
SCIE_AVG
The sections below describe and discuss the various options which
are available to perform the needed operations. These sections discuss
bias corrections, techniques for computing averages, techniques for
cleaning images and removing specific defects, and finally how to
use the COMPUTE command for dark subtraction and flat fielding.
Pascal Ballester
Tue Mar 28 16:52:29 MET DST 1995