Hakucho (also known as CORSA-b before launch) was Japan's first X-ray astronomy satellite, developed by the Institute of Space and Aeronautical Science (then a division of the University of Tokyo). It was launched by the ISAS M-3C-4 rocket on February 21, 1979 and reentered the atmosphere on April 16, 1985.
It was a replacement for the CORSA satellite which failed to launch due to rocket failure on February 4, 1976.
- Discovery of soft X-ray transient Cen X-4 and Aql X-1
- Discovery of many burst sources
- Long-term monitoring of X-ray pulsar (e.g. Vela X-1)
- Discovery of 2 Hz variability in the Rapid Burster later named Quasi Period Oscillation.