Calibration Access and Data Handbook

Generation from In-Orbit Data

A direct measurement of the curve of growth of the PSF is limited by the small number of appropriate, isolated stars and the large scatter caused by coincidence loss and straylight. Thus we have used Daophot for our PSF analysis. This allows us to fit the same function to all the stars in a field of view, thus giving a set of good average PSFs for a range of count to framerate ratios(CFRR). This CCF has been achieved from in-flight data for all filters and is already incorporated into the SAS.