The EUV spectrophotometer on Atmosphere Explorer

An extreme ultraviolet (EUV) spectrophotometer for measurements of solar radiation at wavelengths ranging from 140 to 1850 Å will be included in the payload of each of the three Atmosphere-Explorer (AE) missions, AE-C, -D, and -E. The instrument consists of 24 grating monochromators, 12 of which can be telecommanded either to execute 128-step scans each covering a relatively small section of the total spectrophotometer wavelength range or to maintain fixed (command-selected) wavelength positions. The remaining 12 nonscan monochromators operate at permanently fixed wavelengths and view only a small fraction of the solar disk except for one viewing the whole sun in H Lyman α. Ten of the 12 scan-capable monochromators also view the entire solar disk since their primary function is to measure the total fluxes independent of the distribution of sources across the solar disk. The narrow angular fields of view of the other monochromators allow good height resolution of atmospheric-absorption analyses to be extended to altitudes as low as 90 to 100 km, based on occultation observations made near satellite sunrise and sunset.