The instantaneous field of view
The instantaneous field of view (IFOV) is given in the form of a attenuation in magnitude as a function of separation in arcsec. The original measurements are shown as red dots, the fitted curve as used in the data processing, is shown in green. The original measurements extend much further than 35 arcsec, but there was no application for distances beyond that value.
Double stars with separations beyond about 12 arcsec systematically show combined modulation amplitudes that are larger than would be expected based on the mean flux, indicating that a further calibration is needed for the attenuation of the harmonic amplitude with separation. This would have to be derived from the available wide-binary observations.