One of two NASA orbiting ultraviolet observatories flown on Spacelab missions aboard the space shuttle in 1990 and 1995. Each observatory measured ultraviolet radiation from celestial objects, such as planets, stars, quasars, and nebulae (clouds of gas and dust). They each carried three instruments: the Hopkins Ultraviolet Telescope (HUT), the Ultraviolet Imaging Telescope (UIT), and the Wisconsin ultraviolet photo-polarimetry experiment (WUPPE). Astro 1 was launched on 2 December 1990 on Columbia and made 231 observations of 130 celestial objects during its ten-day flight. Astro 2 was launched on 2 March 1995 on Endeavour and made 385 observations of 260 celestial objects during 16.5 days, producing five times as much data as the first mission.