Tenma was a Japanese X-ray astronomy satellite, launched by ISAS (Institute of Space and Astronautical Science). It carried detectors developed at the Goddard Space Flight Center with a greater energy resolution (by a factor of two) than proportional counters and performed the first sensitive measurements of the iron spectral region for many cosmic sources. Tenma, which means "Pegasus," was known before launch as Astro-B (see Astro- series). It stopped operating in October 1985.