Solar spectral irradiance observations between 200 and 360 NM made during the Atlas 1 mission: Comparisons between the SOLSPEC, SUSIM, and SSBUV measurements

The SOLSPEC, SSBUV, and SUSIM spectrometers observed the solar spectral irradiance simultaneously during the ATLAS-1 mission flown on board the Space Shuttle in March 1992. The three instruments use different methods and means of absolute calibration and were calibrated pre- and post-flight. The three data sets are reported from 200-360 nm at 1.1 nm resolution. The method of comparing the three independent data sets will be discussed. The importance of a common precise wavelength scale will be shown when comparing the data in the wavelength region of the strong Fraunhofer lines. The consistency of the three measurements is better than 5%. The fact that the calibrations of the three instruments were based on three independent national standards ensures that the absolute solar spectral irradiance in the range of 200-360 nm is now known with an accuracy of better than 5%. The data taken from this mission are compared with solar observations from other space based missions.