Reference File Types

The saturation step uses a SATURATION reference file.

CRDS Selection Criteria

Saturation reference files are selected on the basis of INSTRUME, DETECTOR, and SUBARRAY values from the input science data set.

SATURATION Reference File Format

Saturation reference files are FITS format with with 2 IMAGE extensions: SCI and DQ, which are both 2-D integer arrays, and 1 BINTABLE extension.

The values in the SCI array give the saturation threshold in units of DN for each pixel. The saturation reference file also contains a DQ_DEF table extension, which lists the bit assignments for the flag conditions used in the DQ array.

The BINTABLE extension uses EXTNAME=DQ_DEF and contains the bit assignments of the conditions flagged in the DQ array, and contains 4 columns:

• BIT: integer value giving the bit number, starting at zero
• VALUE: the equivalent base-10 integer value of BIT
• NAME: the string mnemonic name of the data quality condition
• DESCRIPTION: a string description of the condition