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How do I find the correct reference Transfer Function for the analysis of my double star Transfer Function?

Q: How do I find the correct reference Transfer Function for the analysis of my double star Transfer Function?

A: All available reference Transfer Functions are available from the FGS Transfer Mode Calibration Products page. The calibration reference file used should represent an observation taken through the same filter as the observed Transfer Function. It should also be close to the same position in the field of view and as close as possible in time to the observation. The target of the reference file used should have a color index close to that of the science target.

Data taken after day 352 of 1993 should NOT use any reference files before that date. Similarly, data taken before day 352 of 1993 should NOT use any reference files after 18 Dec. 1993. [The secondary mirror of the Hubble Space Telescope was moved on that date and the morphology of the Transfer Function changed considerably as a result.]