Title
HEAO A-1 ALL-SKY X-RAY CATALOG"

Dimensions
Sight 34 x 50 cm
Frame 46 x 63 cm

Condition Report
Overall good.

The HEAO A-1 All-Sky X-ray Catalog is a catalog of celestial X-ray sources detected by the HEAO-1 satellite during its mission from 1977 to 1979. The catalog contains information on over 3,000 sources detected in the energy range of 0.15 to 10 keV, covering the entire sky.

The HEAO-1 satellite was the first X-ray observatory to perform an all-sky survey, providing a comprehensive view of the X-ray universe. The A-1 catalog was compiled from the survey data and was released in 1984. It contains information on the position, flux, spectral hardness ratio, and variability of each source.

The catalog has been used extensively in X-ray astronomy research and has led to many important discoveries, including the first identification of X-ray binary stars, the discovery of X-ray emitting clusters of galaxies, and the detection of X-ray emission from active galactic nuclei.