High Energy Astronomy Observatory 1

High Energy Astronomy Observatory 1

Names	HEAO-1, HEAO-A
Mission type	orbiter
Operator	NASA
COSPAR ID	1977-075A
SATCAT no.	10217
Mission duration	1 year, 7 months and 2 days
Spacecraft properties
Manufacturer	TRW
Payload mass	2,551.9 kg (5,626 lb)
Dimensions	height:5.68 m (18.6 ft) radius: 2.67 m (8 ft 9 in)
Start of mission
Launch date	12 August 1977
Rocket	Atlas Centaur
Launch site	CCAFS LC-36B[1]
End of mission
Deactivated	9 January 1979
Decay date	14 March 1979
Orbital parameters
Eccentricity	0
Perigee altitude	432 km (268 mi)
Apogee altitude	432 km (268 mi)
Inclination	23°
Period	93.5 min
Epoch	13 August 1977 00:00:00 UTC

HEAO-1 was an X-ray telescope launched in 1977. HEAO-1 surveyed the sky in the X-ray portion of the electromagnetic spectrum (0.2 keV – 10 MeV), providing nearly constant monitoring of X-ray sources near the ecliptic poles and more detailed studies of a number of objects by observations lasting 3–6 hours. It was the first of NASA's three High Energy Astronomy Observatories, HEAO 1, launched August 12, 1977 aboard an Atlas rocket with a Centaur upper stage, operated until 9 January 1979. During that time, it scanned the X-ray sky almost three times

HEAO included four X-ray and gamma-ray astronomy instruments, known as A1, A2, A3, and A4, respectively (before launch, HEAO 1 was known as HEAO A). The orbital inclination was about 22.7 degrees. HEAO 1 re-entered the Earth's atmosphere on 15 March 1979.