Comparison of Super-Sky and Self-Calibration Flat Fields for Simulated Mid-Infrared JWST Images

The efficacy of two different flat-field calibration methods for JWST are considered. Flat fields obtained by the co-addition of sky flats and those obtained via self-calibration are quantitatively compared. Both methods can produce flat fields with an accuracy of a few parts in 105 that satisfy the JWST science requirements, as long as the instrumental response and background properties remain constant over several observing programs. The self-calibration method is quantitatively better, and is potentially more robust with respect to long-term changes in detector properties. The simpler super-sky flat method is probably preferable if instrumental and detector properties remain stable at the required level of accuracy.