http://hesperia.gsfc.nasa.gov/sftheory/yohkoh.htm
Yohkoh (``Sunbeam'' in Japanese) is a satellite dedicated to high-energy observations of the Sun, specifically of flares and other coronal disturbances. The Yohkoh mission was launched on August 30, 1991, from the Kagoshima Space Centre in southern Japan. The spacecraft carries a payload of four scientific instruments: the Soft X-ray Telescope (SXT), the Hard X-ray Telescope (HXT), the Bragg Crystal Spectrometer (BCS) and the Wide Band Spectrometer (WBS). The SXT (which is sensitive in the range 1-2 KeV) takes images in various wavebands (selected by filters) using a CCD - either the full CCD frame, or a selected part of the CCD frame is returned in telemetry - these are known as full frame, and partial frame images (FFI and PFI); the HXT (which is sensitive in the range 10-100 KeV) measures Fourier components in 4 channels through a set of 64 pairs of grids - the images are reconstructed on the ground; the BCS observes the line complexes of Fe XXVI, Fe XXV, Ca XIX and S XV using bent germanium crystals; and the WBS observes the overall energy release between soft X-rays and gamma-rays using three separate instrument packages.