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This third High-Energy Astronomy Observatory (HEAO) mission performed a sky survey of gamma rays and cosmic rays in a manner similar to HEAO 1. It had a higher orbital inclination than the previous missions in this series, since the payload consisted primarily of cosmic-ray instrumentation; greater cosmic-ray flux occurs near the earth's magnetic poles. The scientific objectives of the mission were (1) to determine the isotopic composition of the most abundant components of the cosmic-ray flux with atomic mass between 7 and 56, and the flux of each element with atomic number (Z) between Z = 4 and Z = 50; (2) to search for super-heavy nuclei up to Z = 120 and measure the composition of the nuclei with Z >20; (3) to study intensity, spectrum, and time behavior of X-ray and gamma-ray sources between 0.06 and 10 MeV; measure isotropy of the diffuse X-ray and gamma-ray background; and perform an exploratory search for X-and gamma-ray line emissions. The normal operating mode was a continuous celestial scan about the Z axis (which nominally pointed to the sun).

Alternate Names

  • 11532
  • HEAO-C
  • HEAO3
  • High Energy Astron Obs-C

Facts in Brief

Launch Date: 1979-09-20
Launch Vehicle: Atlas-Centaur
Launch Site: Cape Canaveral, United States
Mass: 2660 kg

Funding Agency

  • NASA-Office of Space Science (United States)


  • Planetary Science
  • Space Physics
  • Astronomy

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Mr. Richard E. HalpernProgram ManagerNASA Headquarters
Dr. John F. StoneProject ManagerNASA Marshall Space Flight Center
Dr. Thomas A. ParnellProject ScientistNASA Marshall Space Flight
Dr. Albert G. OppProgram ScientistNASA Headquarters

Related Information/Data at NSSDCA

HEAO 2 (Einstein Observatory)

US Active Archive for HEAO 3 Information/Data

The HEAO 3 Archive at HEASARC

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