title: Calibration Changes in EUV Solar Satellite Instruments.
abstract: This paper reviews the problem of absolute photometric calibration in the extreme uv range with particular reference to a solar satellite instrument. EUV transfer standards, the use of predispersing spectrometers, and polarization effects at near normal incidence are discussed. Changes in preflight calibration associated with the general problems of contamination are given as the background to the main discussion relating to changes in photometric calibration during orbital operation. Conclusions relating to adequate photometric measurements in orbit are drawn, with a short list of the "best" solar flux measurements for reference. Finally, the importance of rocket flights for photometric calibration of satellite instruments is indicated.
authors.forename: E M
authors.initials: EM
authors.lastname: Reeves
authors.forename: W H
authors.initials: WH
authors.lastname: Parkinson