- ID:
- ivo://nasa.heasarc/a4
- Title:
- HEAO 1 A4 Catalog of High-Energy X-Ray Sources
- Short Name:
- A4
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The HEAO 1 A-4 Catalog of High-Energy X-ray Sources represents results from an all-sky survey carried out at high X-ray energies (13-180 keV) from August 1977 until January 1979 using data obtained with the UCSD/MIT Hard X-Ray and Low-Energy Gamma-Ray Instrument on the HEAO 1 satellite. Quantitative results from a model-dependent fitting procedure are given in the form of fitted count rates in four broad energy bands for about 70 sources. The survey is complete, except in regions of source confusion, down to an intensity level of about 1/75 of the Crab Nebula in the 13-80 keV energy band. Forty-four sources were detected in the 40-80 keV energy band, and 14 in the 80-180 keV band. Most of the sources are galactic; seven are extragalactic. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/a2led
- Title:
- HEAO 1 A2 LED Catalog
- Short Name:
- A2LED
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- 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 .
- ID:
- ivo://nasa.heasarc/a1
- Title:
- HEAO 1 A1 X-Ray Source Catalog
- Short Name:
- A1
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The HEAO 1 A-1 X-Ray Source Catalog contains information about X-ray sources detected with the NRL Large Area Sky Survey Experiment (also referred to as the A-1 Experiment) flown aboard the HEAO-1 satellite. The catalog represents results from the first six months of data from HEAO-1, during which time a scan of the entire sky was completed. Positions and intensities for 842 sources are listed, with a limiting flux of 250 nanoJanskies (nJy) at 5 keV, or about 0.25 Uhuru flux units (UFU). The catalog is more than 90% complete at a flux level equivalent to 1.5 microJanskies (µJy) at 5 keV, for a Crab-like spectrum. The A-1 catalog has been cross-referenced with published literature. Identifications based on coincidence in position have been proposed for some of the sources for which previous work has established no firm identification. Half of the sources remained unidentified at the time of catalog publication (1984). The A3 database contains a list of 654 optical objects identified with A-1 error boxes. Minor structural changes were made to this database table and the documentation was revised by the HEASARC in July 2004. The basic content of the database table was unchanged, however. This is a service provided by NASA HEASARC .
