This program allows one to estimate the effective pupil size over a science integration, given the declination, visit length, crsplit, and setup time. This program assumes that the visit (including setup time) will be centered upon the center of the trajectory, and uses a bi-linear approximation to the pupil diminution off axis.
Enter the declination, visit length, crsplit, and setup time below and hit the submit button.
You can also download a code that will look at your fits files to determine what the filling factor actually was for any given science observation, assuming the bi-linear model for axial dependence of the pupil size. The code is called checkfill.