|Mission type||X Ray Celestial Observation|
|Operator||Institute of Space and Astronautical Science (Japan)|
|Launch mass||96.0 kilograms (211.6 lb)|
|Start of mission|
|Launch date||21 February 1979 UTC|
|Rocket||M-3C-Rocket (mission 4)|
|Launch site||Uchinoura Space Center, Kagoshima Prefecture, Japan|
|End of mission|
|Decay date||April 15, 1985|
Hakucho (also known as CORSA-b before launch; CORSA stands for Cosmic Radiation Satellite) 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 rocket on the M-3C-4 mission on February 21, 1979 and reentered the atmosphere on April 15, 1985.
It was a replacement for the CORSA satellite which failed to launch due to rocket failure on February 4, 1976.