A Japanese satellite, with US and UK involvement, launched in 1991 August to study flares and other solar activity at X-ray and gamma-ray wavelengths. The name means ‘sunbeam’ in Japanese. Yohkoh carried four instruments: a Soft X-ray Telescope (SXT), a Hard X-ray Telescope (HXT), a Bragg Crystal Spectrometer (BCS), and a Wide Band Spectrometer (WBS). It ceased observations in 2001 December and re-entered the Earth's atmosphere in 2005 September.
http://www.isas.jaxa.jp/e/enterp/missions/yohkoh/index.shtml Mission page at Japan Aerospace Exploration Agency.
Subjects: Astronomy and Astrophysics.