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The Tenma [Astro B] Satellite

artist concept of Tenma
Credit: JAXA

Astro B was the second Japanese X-ray astronomy satellite. After launch on February 20, 1983, it was renamed Tenma (Japanese for "Pegasus"). Tenma carried GSFC detectors which had an improved energy resolution (by a factor of 2) compared to proportional counters and performed the first sensitive measurements of the iron spectral region for many astronomical objects.

Mission Characteristics

* Lifetime: February 20, 1983 - November, 22 1985
* Energy Range: 0.1 keV - 60 keV
* Payload:
  • Gas Scintillator Proportional Counter: 10 units of 80 cm2 each, FOV ~ 3deg (FWHM), 2 - 60 keV
  • X-ray focusing collector: 2 units of 7 cm2 each, 0.1 -2 keV
  • Transient Source Monitor: 2 - 10 keV
  • Radiation Belt Monitor/Gamma-ray burst detector
* Science Highlights:
  • 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
* Archive: Not Available at HEASARC (
[About Tenma] ( [Gallery] ( [Publications] (

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