1st High Energy Astrophysics Observatory

The first of NASA's three High Energy Astronomy Observatories, HEAO 1 was launched aboard an Atlas rocket with a Centaur upper stage on 12 August 1977 and operated until 9 January 1979. During that time, it scanned the X-ray sky almost three times over 0.2 keV - 10 MeV, provided nearly constant monitoring of X-ray sources near the ecliptic poles, as well as more detailed studies of a number of objects through pointed observations.