Solar EUV irradiance from the San Marco Assi: A reference spectrum

The only satellite measurement of the solar EUV irradiance during solar cycle 22 has been obtained with the Airglow Solar Spectrometer Instrument (ASSI) aboard the San Marco 5 satellite flown in 1988. The ASSI in‐flight calibration parameters are established by using the internal capabilities of ASSI and by comparing ASSI results to the results from other space‐based experiments on the ASSI calibration rocket and the Solar Mesospheric Explorer (SME). A solar EUV irradiance spectrum derived from ASSI observations on November 10, 1988 is presented as a reference spectrum for moderate solar activity (F_10.7≈ 150) for the aeronomy community. This ASSI spectrum should be considered as a refinement and extension of the solar EUV spectrum published for the same day by Woods and Rottman [1990]. This new reference solar spectrum covers the wavelength range from 20 to 200 nm and is presented in a format similar to the 37 wavelength intervals defined by Torr and Torr [1985].