High resolution rocket EUV solar spectrograph.

The design and performance of an Aerobee 150 rocket-borne solar spectrograph covering a wavelength range of 10 to 385 A are discussed. The spectrograph uses a gold-coated replica concave grating of 3-m radius with 1200 grooves/mm at an angle of incidence of 88 deg. The spectra are recorded on glass photographic plates making possible wavelength determination to 0.003 A if known standard wavelengths occur frequently enough. Special attention to scattered light made possible the photographing of the solar spectrum from 60 to 385 A without using filters to absorb the strong visible and UV sunlight, although the solar spectrum was also recorded through metal foil filters. In the laboratory the spectrograph has been used to record spectra of highly ionized metals with a resolution of 0.03 A or better.