The solar disk spectrum between 660 and 1175 Å (first order) obtained by SUMER on SOHO

Abstract

SUMER - Solar Ultraviolet Measurements of Emitted Radiation - onboard of SOHO - Solar and Heliospheric Observatory - obtained its first spectrum on January 25, 1996 near the north polar limb. The range from 660 Å to 1175 Å which has never before been observed with such a good spectral resolution contains a wealth of spectroscopic details. Identification of about 400 lines in this spectral range is given. We list the wavelengths of identified transitions and provide their absolute peak intensities. General spectral features of the most abundant elements H, He, C, N, O, Ne, Mg, Si, S, Ar, and Fe are described. In this spectral range many density- and temperature-sensitive line pairs are found. It is shown in examples how they can be used as diagnostic tools.