HEAO 1 A2 LED Catalog

The HEAO 1 A-2 LED Catalog of High-Energy X-ray Sources is the result of a study of the diffuse X-ray sky over the bands of X-ray energies 0.18-0.44 keV and 0.44-2.8 keV from August 1977 until January 1979 using data obtained with the A-2 Low Energy Detector on the HEAO 1 satellite. The HEAO A-2 Experiment was primarily designed for studying the diffuse X-ray background; however, it was also capable of studying point sources to good sensitivity. The detectors surveyed over 95 percent of the sky in the spectral bands listed above to typical limiting sensitivities of 1x10-11 and 3x10-11 respectively. Using a significance criterion of 6 sigma for existence, 114 sources are cataloged. The catalog contains a list of all counterpart identifications and a cross-reference to all HEAO 1 A-2 LED team publications on the catalog sources complete through the end of 1981. The identified sources fall into several categories, primarily dependent on observing energy interval. In the 1 KeV band the sources include: 20 galactic stellar sources, 19 extragalactic sources, 13 SNR's, 11 galactic bulge sources, 2 globular cluster sources, and 2 previously reported sources without optical counterparts. In the .25 KeV band the sources include: 24 galactic stellar objects, 12 extragalactic sources, 5 SNR's, 1 bulge source, and 1 globular cluster source. This is a service provided by NASA HEASARC .

Data and Resources

Additional Info

Field Value
Maintainer Tess Jaffe
Last Updated May 12, 2025, 01:06 (UTC)
Created April 1, 2025, 12:45 (UTC)
accessLevel public
bureauCode {026:00}
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harvest_source_id b99e41c6-fe79-4c19-bbc3-9b6c8111bfac
harvest_source_title Science Discovery Engine
identifier ivo://nasa.heasarc/a2led
modified 2025-05-12T00:55:29Z
programCode {026:000}
publisher High Energy Astrophysics Science Archive Research Center
resource-type Dataset
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theme {Astrophysics}