In the past, instruments that undergo evolution of calibration files or calibration software often required users to carry out their own recalibrations at their home sites. With OTFC, the HST data archives carry out the recalibration.
In the past, instruments that changed through calibration file or software updates often necessitated user-initiated recalibrations at home sites. With OTFC, HST data archives take on the responsibility of recalibration.