The linearity correction step uses a LINEARITY reference file.
CRDS Selection Criteria¶
Linearity reference files are selected by INSTRUME and DETECTOR.
Reference File Format¶
Linearity reference files are FITS format with 2 IMAGE extensions and 1 BINTABLE extension. The primary data array is assumed to be empty. The 2 IMAGE extensions have the following characteristics:
|COEFFS||3||ncols x nrows x ncoeffs||float|
|DQ||2||ncols x nrows||integer|
Each plane of the COEFFS data cube contains the pixel-by-pixel coefficients for the associated order of the polynomial. There can be any number of planes to accomodate a polynomial of any order.
The BINTABLE extension uses
EXTNAME=DQ_DEF and contains the bit assignments
of the conditions flagged in the DQ array.