High-spectral-resolution solar irradiance in the 184.5 to 232.5 nm range from the SOLSPEC and UVSP spectrometers

The study of the minor constituents of the planetary atmospheres from the a nalysis of the scattered light properties requires the knowledge of the abs olute incident solar irradiance at high resolution. The data were obtained from the UVSP experiment on board the Solar Maximum Mission satellite in th e 184.5-232.5 nm spectral range. We have reconstituted the solar spectrum m easured in three different regions of the solar disk with a spectral resolu tion of 0.01 nm and a spatial resolution of 3 arc sec. The wavelength scale was determined with a standard deviation of 0.0025 nm. The comparison of t he relative intensities in three locations of the solar disk with those obt ained by other authors allowed us to determine these positions accurately a nd to derive the integrated spectrum of the whole disk. Finally, the result ing spectrum has been expressed in absolute units using the spectral irradi ance by the SOLSPEC and SUSIM spectrometers, respectively operated with the ATLAS 1 mission and from the Upper Atmosphere Research Satellite. We obtai ned the absolute solar irradiance with an accuracy of 10% in the 184.5-232. 5 nm spectral range with a spectral resolution of 0.01 nm for the first tim e using data from space observations.