Yohkoh

Yohkoh (ようこう, Sunbeam in Japanese), known before launch as Solar-A, was a Solar observatory spacecraft of the Institute of Space and Astronautical Science (Japan), in collaboration with space agencies in the United States and the United Kingdom. It was launched into Earth orbit on August 30, 1991 by the M-3S-5 rocket from Kagoshima Space Center. It took its first image on September 13, 1991 21:53:40.

Description

The satellite was three-axis stabilized and in a near-circular orbit. It 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). About 50 MB were generated each day and this was stored on board by a 10.5 MB bubble memory recorder.

Because the SXT utilized a charge-coupled device (CCD) as its readout device, perhaps being the first X-ray astronomical telescope to do so, its "data cube" of images was both extensive and convenient, and it revealed much interesting detail about the behavior of the solar corona. Previous solar soft X-ray observations, such as those of Skylab, had been restricted to film as a readout device. Yohkoh therefore returned many novel scientific results, especially regarding solar flares and other forms of magnetic activity.