Reference File Types

The default algorithm in the MIRI MRS stray-light correction step uses information contained in the meta data of the input image which maps each pixels to a slice or the region between the slices, also known as the slice gaps. This information was previously loaded from a reference file into the meta data by the assign_wcs step. There is an option to use a more simplistic algorithm that uses stray-light mask reference file.

CRDS Selection Criteria

If –method = “Nearest” option is used then the MIRI MRS stray-light reference file is selected on the basis of INSTRUME, DETECTOR, and BAND values of the input science data set.

MIRI MRS stray-light Reference File Format

The stray-light mask reference files are FITS files with and empty primary data array and one IMAGE extension. This IMAGE extension is a 2-D integer image mask file of size 1032 X 1024. The mask contains values of 1 for pixels that fall in the slice gaps and values of 0 for science pixels. The stray-light algorithm only uses pixels that fall in the slice gaps to determine the correction.