Thirty-five years ago today — August 12– High-Energy Astronomy Observatory 1 (HEAO 1) was launched by an Atlas Centaur from Cape Canaveral.
(X-ray source catalog from HEAO-1’s all-sky survey. NASA image.)
HEAO 1 was the first satellite in a series of three to study X-ray and gamma-ray sources. HEAO 1, in particular,
was specifically designed to map and survey the celestial sphere for X-ray and gamma-ray sources in the energy range of 150 eV to 10 MeV, to establish the size and precise location of X-ray sources to determine the contribution of discrete sources to the X-ray background, and to measure time variations of X-ray sources.
The HEAO 1 observatory was capable of scanning the entire celestial sphere in 6 months, but failure of some of the detector components meant the complete survey took longer than planned. In addition, the instruments had to be turned off when passing through the inner Van Allen radiation belt to protect itself from damage. The mission lasted until January 9, 1979, during which HEAO 1 compiled a comprehensive catalog of X-ray sources, classified several hundred X-ray source with their visible-light companions, and discovered the first X-ray eclipse in a low-mass binary star.
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