HEAO 3

Description

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).