EURD Observations of EUV Nightime Airglow Lines

The extreme ultraviolet (EUV) airglow has yet to be studied extensively due to observational difficulties in this range of the spectrum. EURD is an instrument designed to study diffuse EUV radiation flown on the Spanish MINISAT-01 satellite. In this paper we present observations of the terrestrial night airglow as observed from EURD in the range of 400 to 1060 Å. The high sensitivity and high resolution of the instrument, compared with previous observations, and the long integration times provided by MINISAT-01 permits the identification for the first time of the complete Lyman series of atomic hydrogen resolving up to Lyman ǫ. It has also been possible to identify a feature at 537 Å as helium Lyman β line and the detection of other lines of the blended Lyman series of helium at 515 and 522 Å.