For each pixel, a value of zero in the data quality file indicates that there is no known problem with the corresponding pixel in the science file. If because of data-dropouts the datum has been filled, the data quality value is 16. If the datum failed the Reed-Solomon error check, the data quality value is 1. For spectrographic images, geometric correction is done first, so it is the C0 image that is fully corrected. The C2 file is a list of the locations of reseau marks found in the raw flat field.
Positions are in photocathode coordinates.
CG cg.fits Geometrically corrected image if no flat-field correction is done. Flat-fielded image if no geometric correction is done.