• Joint German/UK/US satellite, launched in 1990 and operational until 1999, which produced a map of the sky at wavelengths in X-rays and the extreme ultraviolet especially in the 5–10 Angstrom range. Called the Roentgen Satellite in honour of Wilhelm Roentgen, discoverer of X-rays. It has identified tens of thousands of new X-ray sources and helped elucidate processes including the latter stages of solar evolution such as supernova explosions and the formation of starburst galaxies.