Airglow-solar spectrometer instrument (20–700 nm) aboard the San Marco D/L satellite

The ASSI experiment aboard the San Marco D/L aeronomy satellite will monitor the airglow, solar, and interplanetary radiations from the EUV through the visible spectral regions. Four spectrometers with solar pointing control cover this broad region using channels with eighteen overlapping wavelength ranges with spectral resolutions from 0.8 to 3.0 nm are adequate for aeronomy. Large dynamic ranges up to 1:1011 permit the measurement of faint airglow or interplanetary radiation and intense solar emissions with one and the same instrument. Instrumental details such as the special optical design and calibration procedures are presented in detail.