Data Reduction Frequently Asked Questions
Processing of my NIR daytime calibration data fails - why?
In the NIR arm all arc lamp and flat field calibrations are taken with the lamp switched on (ON frames) and off (OFF frames). The OFF frames are needed to correct for the dark current. If they are not present the recipes xsh_predict, xsh_orderpos, xsh_2dmap, xsh_mflat and xsh_wavecal will fail.