Tenma (Japanese for "Pegasus").
Tenma, known as Astro-B before launch, was Japan's second X-ray astronomy satellite, developed by the Institute of Space and Astronautical Science. It was launched on February 20, 1983 using a M-3S-3 rocket as the vehicle.
Battery failure in July 1984 caused the operation to become limited, and continuing problems lead to the termination of X-ray observation in 1985. It reentered the atmosphere on January 19, 1989.
- Discovery of the iron helium-like emission from the galactic ridge
- Iron line discovery and/or study in many LMXRB, HMXRB and AGN
- Discovery of an absorption line at 4 keV in the X1636-536 Burst spectra