GHRS Instrument Handbook
Calibration is of three types: characterization, monitoring, and special tests. Characterization is the detailed determination of instrument properties, either initially, or at a later time if thought necessary. Monitoring consists of an ongoing series of short tests to check that the instrument continues to operate normally. Special tests are one-time programs to check a new operating feature or the like.
Aside from the one-time changes imposed by COSTAR and the reactivation of Side 1, the GHRS has been a very stable and reliable instrument. Therefore the calibration programs for Cycles 5 and 6 consist mostly of monitoring programs, with a few special tests and one characterization. What we measure is our ability to establish the wavelength and flux scales of spectra. We also check basic properties of the detectors on a regular basis and examine other aspects of the instrument.