The X-ray spectrometer experiment on the first spacelab flight

The First Spacelab Flight - scheduled for September 1983 - will carry a multidisciplinary payload intended to demonstrate that valuable scientific results can be achieved with such short duration missions. The payload complement includes a spectrometer to undertake observations of the brighter cosmic X-ray sources. The primary scientific objectives of this experiment are the study of detailed spectral features in cosmic X-ray sources and their associated temporal variations over a wide energy range from about 2 keV up to 80 keV. The instrument based on the gas scintillation proportional counter, will have an effective area of some 180 cm² with an energy resolution of ～ 9% FWHM at 7 keV. The key performance parameters of the instrument, which include calibration results and the sensitivity of the planned observations, are discussed.