The IRAF CCD Reduction Package -- CCDRED

The IRAF† CCD reduction package, ccdred, provides tools for the easy and efficient reduction of CCD images. The standard reduction operations are replacement of bad pixels, subtraction of an overscan or prescan bias, subtraction of a zero level image, subtraction of a dark count image, division by a flat field calibration image, division by an illumination correction, subtraction of a fringe image, and trimming unwanted lines or columns. Another common operation provided by the package is scaling and combining images with a number of algorithms for rejecting cosmic rays. Data in the image header is used to make the reductions largely automated and self-documenting though the package may still be used in the absence of this data. Also a translation mechanism is used to relate image header parameters to those used by the package to allow data from a variety of observatories and instruments to be processed. This paper describes the design goals for the package and the main tasks and algorithms which satisfy these goals. This paper is to be published as part of the proceedings of the Santa Cruz Summer Workshop in Astronomy and Astrophysics, Instrumentation for Ground-Based Optical Astronomy: Present and Future, edited by Lloyd B. Robinson and published by Springer-Verlag. †Image Reduction and Analysis Facility (IRAF), a software system distributed by the National Optical Astronomy Observatories (NOAO).