|Space Telescope Science Institute|
|FGS Instrument Handbook Cycle 23|
2.7 For the most part, the calibration requirements of the current Cycle’s GO science programs will be supported by STScI. For Position mode observations, this includes the optical field angle distortion (OFAD) calibration, cross-filter effects, lateral color effects, and the routine monitoring of the changes in distortion and scale across the FOV.For Transfer mode, STScI will calibrate the interferograms (S-Curves) as a function of a star’s spectral color. In addition, the S-Curves will be monitored for temporal stability.