Photometric calibration of the EUV spectroheliometer on ATM

Abstract
This paper describes the derivation of the preflight photometric calibration of the uv spectrometer on Sky-lab. The calibration of the orbiting instrument through cross-comparison with two rocket instruments is discussed in assessing the observed changes in response to quiet solar regions during the mission. Formulas are presented for the determination of the instrument sensitivity, and an uncertainty of ±35% is assigned over most of the 296–1340-Å wavelength range.