WCS calibration and creating single images from multiple extensions 1. This can be automatically set in the login.cl file. Define what should be sorted. This works as a place holder in the selection criteria and will be removed after selection.
Crosstalk are artifacts arising in the CCDs due to multiple amplifiers.
The coefficients will correct this problem, once applied. It's possible to compare these coefficient with the values on the CTIO Mosaic webpage. Choose an object file for this. The computed values of the coefficients must be applied to all .fits files. Crosstalk corrections, overscan, and trim can be done simultaneously.