Thirty years ago today — May 26, 1983 — the European X-ray Observatory Satellite was launched from Vandenberg AFB on a Delta rocket.
(EXOSAT. NASA image.)
EXOSAT was built to study cosmic X-ray sources from a highly eccentric orbit. The satellite operated until April 1986 and “made 1780 observations of a wide variety of objects, including active galactic nuclei, stellar coronae, cataclysmic variables, white dwarfs, X-ray binaries, clusters of galaxies, and supernova remnants,” according to this European Space Agency page.by