Yohkoh is a Japan/US/UK mission aiming for the study of high-energy solar physics. Its scientific operations were conducted since early September-1991 until 14-December-2001, while its orbital life was from 31-August-1991 to 12-September-2005. Yohkoh was named after the Japanese word meaning 'sunshine'.

Yohkoh scientific instrumentation included a Hard X-ray Telescope (HXT), a Soft X-ray Telescope (SXT), a Bragg Crystal Spectrometer (BCS), and a Wide-Band Spectrometer (WBS). These instruments are described in a series of papers in Solar Physics, vol. 136 (1991). First results have been published in Publ. Astron. Soc. Japan, vol 44 (1992). A bibliography of Yohkoh-related publications may be found at http://www.lmsal.com/~aschwand/publications/yohkoh.html.

Yohkoh steadily continued its observation more than ten years, and this made Yohkoh the world's first space mission to provide solar images over a whole solar cycle. On 14-Dec-2001, however, observing an annular eclipse Yohkoh lost its attitude control and became unable to resume observations.

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