A2LED ivo://nasa.heasarc/a2led NASA/GSFC HEASARC Nugent et al. 2026-07-17 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source 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 . 1983ApJS...51....1N https://heasarc.gsfc.nasa.gov/W3Browse/all/a2led.html Archive Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=a2led& GET text/xml 180 99999 true 351.786431827455 -79.3748264660302 1 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=a2led GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_a2led&Action=More+Options&Action=Parameter+Search&ConeAdd=1 HEAO1 1 X-ray public a2led HEAO 1 A2 LED Catalog name Target Designation meta.id;meta.main char nullable othername Alternative Designation #1 char nullable ra RA Overlap Error Box (OEB) degree pos.eq.ra;meta.main double nullable dec Declination Overlap Error Box (OEB) degree pos.eq.dec;meta.main double nullable count_rate Source Intensity 1 keV (ct/s) ct/s phot.count;em.X-ray.soft float nullable count_rate_error Error in 1-keV Source Intensity (ct/s) ct/s stat.error;phot.count;em.X-ray.soft 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 boxarea_beb Box Area BEB (degree^2) degree^2 float nullable ra3 Right Ascension (B1950.0) OEB Corner 3 degree double nullable bii Galactic Longitude OEB degree pos.galactic.lat double nullable othername3 Alternative Designation #3 char nullable boxarea_oeb Box Area OEB (degree^2) degree^2 float nullable corner3_ra_beb Right Ascension (B1950.0) BEB Corner 3 degree double nullable ra1 Right Ascension (B1950.0) OEB Corner 1 degree double nullable lii Galactic Latitude OEB degree pos.galactic.lon double nullable corner4_ra_beb Right Ascension (B1950.0) BEB Corner 4 degree double nullable corner1_dec_beb Declination (B1950.0) BEB Corner 1 degree double nullable corner2_ra_beb Right Ascension (B1950.0) BEB Corner 2 degree double nullable othername2 Alternative Designation #2 char nullable dec2 Declination (B1950.0) OEB Corner 2 degree double nullable best_fit_lii Galactic Latitude BEB degree double nullable corner4_dec_beb Declination (B1950.0) BEB Corner 4 degree double nullable dec4 Declination (B1950.0) OEB Corner 4 degree double nullable best_fit_ra Right Ascension (B1950.0) Best-Fit Error Box (BEB) degree double nullable corner1_ra_beb Right Ascension (B1950.0) BEB Corner 1 degree double nullable best_fit_bii Galactic Longitude BEB degree double nullable tfval Transmission Factor, 1.00 If Not Present float nullable best_fit_dec Declination (B1950.0) Best-Fit Error Box (BEB) degree double nullable ra2 Right Ascension (B1950.0) OEB Corner 2 degree double nullable corner3_dec_beb Declination (B1950.0) BEB Corner 3 degree double nullable int_250ev_error Error in 1/4-keV Source Intensity (ct/s) ct/s float nullable ra4 Right Ascension (B1950.0) OEB Corner 4 degree double nullable int_250ev Source Intensity 1/4 keV (ct/s) ct/s float nullable dec1 Declination (B1950.0) OEB Corner 1 degree double nullable comments Comments char nullable corner2_dec_beb Declination (B1950.0) BEB Corner 2 degree double nullable dec3 Declination (B1950.0) OEB Corner 3 degree double nullable