A1 ivo://nasa.heasarc/a1 NASA/GSFC HEASARC Wood et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source 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 . 1984ApJS...56..507W https://heasarc.gsfc.nasa.gov/W3Browse/all/a1.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=a1& GET text/xml 180 99999 true 355.187220068265 -86.1328643460814 1 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=a1 GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_a1&Action=More+Options&Action=Parameter+Search&ConeAdd=1 HEAO1 1 X-ray public a1 HEAO 1 A1 X-Ray Source Catalog name Source Designation (Based on B1950 Coordinates) meta.id;meta.main char nullable ra Centroid Right Ascension (degrees) degree pos.eq.ra;meta.main double nullable dec Centroid Declination (degrees) degree pos.eq.dec;meta.main double nullable "area" Area of Error Box (degrees^2) degree^2 float nullable count_rate Count Rate for Source (counts/cm^2/s) ct/cm^2/s phot.count;em.X-ray float nullable count_rate_error Error of Count Rate (counts/cm^2/s) ct/cm^2/s stat.error;phot.count;em.X-ray float nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable dec1 Declination of Error Box Corner #1 degree float nullable alternate_x_ray_5 Alternative X-Ray Designation char nullable dec3 Declination of Error Box Corner #3 degree float nullable ra1 Right Ascension of Error Box Corner #1 degree float nullable non_x_ray_id_4 Possible Non-X-Ray Identification char nullable alternate_x_ray_7 Alternative X-Ray Designation char nullable non_x_ray_id_2 Possible Non-X-Ray Identification char nullable lii Centroid Galactic Longitude (degrees) degree pos.galactic.lon double nullable non_x_ray_id_3 Possible Non-X-Ray Identification char nullable alternate_x_ray_6 Alternative X-Ray Designation char nullable dec4 Declination of Error Box Corner #4 degree float nullable lambda Centroid Ecliptic Longitude (degrees) degree double nullable ra3 Right Ascension of Error Box Corner #3 degree float nullable alternate_x_ray_4 Alternative X-Ray Designation char nullable alternate_x_ray_3 Alternative X-Ray Designation char nullable alternate_x_ray_1 Alternative X-Ray Designation char nullable dec2 Declination of Error Box Corner #2 degree float nullable beta Centroid Ecliptic Latitude (degrees) degree double nullable ra4 Right Ascension of Error Box Corner #4 degree float nullable ra2 Right Ascension of Error Box Corner #2 degree float nullable alternate_x_ray_2 Alternative X-Ray Designation char nullable bii Centroid Galactic Latitude (degrees) degree pos.galactic.lat double nullable non_x_ray_id_1 Possible Non-X-Ray Identification char nullable