Hinotori (satellite)

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Names Astro-A
Mission type Astronomy
Operator ISAS
COSPAR ID 1981-017A
SATCAT no. 12307
Spacecraft properties
BOL mass 185 kilograms (408 lb)
Start of mission
Launch date 21 February 1981, 00:30:00 (1981-02-21UTC00:30Z) UTC[1]
Rocket Mu-3S
Launch site Mu Pad, Kagoshima
Contractor ISAS
End of mission
Decay date 11 July 1991 (1991-07-12)
Orbital parameters
Reference system Geocentric
Regime Low Earth
Eccentricity 0.00395
Perigee 548 kilometres (341 mi)
Apogee 603 kilometres (375 mi)
Inclination 31.3 degrees
Period 96.2 minutes
Epoch 21 February 1981, 04:30:00 UTC[2]

Hinotori, also known as ASTRO-A before launch, was Japan's first X-ray astronomy satellite. It was developed by the Institute of Space and Astronautical Science (ISAS). Its primary mission was to study of solar flares emanating from the Sun during the solar maximum.[3] It was launched successfully on February 21, 1981 using a M-3S rocket as the vehicle from Uchinoura Space Center (known at the time as Kagoshima). After the start of normal operation, it observed a large solar flare and, a month later, succeeded in observing 41 flares of many sizes from the Sun. It reentered the atmosphere on July 11, 1991.[4]


  • Solar flare X-ray imager (SXT)
  • Solar soft X-ray bright line spectrum analyzer (SOX)
  • Solar soft X-ray monitor (HXM)
  • Solar flare monitor (FLM)
  • Solar gamma ray monitor (SGR)
  • Particle ray monitor (PXM)
  • Plasma electron density measurement instrument (IMP)
  • Plasma electron temperature measurement instrument (TEL)


  • Observational data of the maximum period of solar activity
  • Discovery of high-temperature phenomena reaching up to 50 million °C and clouds of light-speed electrons floating in the corona of the Sun


  1. ^ JAXA, "Catalogue of ISAS Missions" Archived 2014-12-31 at the Wayback Machine.; retrieved 2014-12-23.
  2. ^ "NASA - NSSDCA - Spacecraft - Trajectory Details". nssdc.gsfc.nasa.gov. Retrieved 2018-05-01.
  3. ^ Gunter's Space Page, "Astro A (Hinotori)"; retrieved 2014-12-23.
  4. ^ ISAS, "Solar Observation HINOTORI (ASTRO-A)"; retrieved 2014-12-23.

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