| Hinotori | |
| Names List: | Astro-A |
| Mission Type: | Astronomy |
| Operator: | ISAS |
| Cospar Id: | 1981-017A |
| Satcat: | 12307 |
| Launch Date: | UTC[1] |
| Launch Rocket: | Mu-3S |
| Launch Site: | Mu Pad, Kagoshima |
| Launch Contractor: | ISAS |
| Orbit Reference: | Geocentric |
| Orbit Regime: | Low Earth |
| Orbit Eccentricity: | 0.00395 |
| Orbit Inclination: | 31.3 degrees |
| Orbit Period: | 96.2 minutes |
| Orbit Epoch: | 21 February 1981, 04:30:00 UTC[2] |
| Apsis: | gee |
Hinotori, also known as ASTRO-A before launch, was a Japanese 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] The name Hinotori is the Japanese word for Phoenix.