A4 ivo://nasa.heasarc/a4 NASA/GSFC HEASARC Levine et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source 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 . 1984ApJS...54..581L https://heasarc.gsfc.nasa.gov/W3Browse/all/a4.html Archive Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=a4& GET text/xml 180 99999 true 19.2712489588701 -73.446992595105 1 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=a4 GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_a4&Action=More+Options&Action=Parameter+Search&ConeAdd=1 HEAO1 1 X-ray public a4 HEAO 1 A4 Catalog of High-Energy X-Ray Sources name Name of Object meta.id;meta.main char nullable alt_name Alternate name of object, if present meta.id char nullable ra Right Ascension (degrees) degree pos.eq.ra;meta.main double nullable dec Declination (degrees) degree pos.eq.dec;meta.main double nullable lii Galactic Longitude degree pos.galactic.lon double nullable bii Galactic latitude degree pos.galactic.lat double nullable count_rate All data 13-80 keV count rate ct/s phot.count;em.X-ray.hard float nullable count_rate_error All data 13-80 keV count rate error ct/s stat.error;phot.count;em.X-ray.hard 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 alla_count_rate_error All data 13-25 keV count rate error ct/s float nullable s3b_count_rate_error Scan 3, 25-40 keV count rate error ct/s float nullable s1a_count_rate Scan 1, 13-25 keV count rate ct/s float nullable s1cont_count_rate Scan 1, Contamination count rate, 13-25 keV ct/s float nullable s1d_count_rate_error Scan 1, 80-180 keV count rate error ct/s float nullable object_codes Code(s) for previous catalogs or satellites char nullable allb_count_rate_error All data 25-40 keV count rate error ct/s float nullable s3abc_count_rate_error Scan 3, 13-80 keV count rate error ct/s float nullable alld_count_rate_error All data 80-180 keV count rate error ct/s float nullable s2abc_count_rate_error Scan 2, 13-80 keV count rate error ct/s float nullable s2_start Start date of 2nd scan mjd double nullable s2_end End date of 2nd scan mjd double nullable s1c_count_rate Scan 1, 40-80 keV count rate ct/s float nullable s2b_count_rate Scan 2, 25-40 keV count rate ct/s float nullable allb_count_rate All data 25-40 keV count rate ct/s float nullable s2a_count_rate_error Scan 2, 13-25 keV count rate error ct/s float nullable allb_flux 25-40 keV flux in ergs cm-2 s-1 keV-1 erg/cm^2/s/keV float nullable s3cont_count_rate Scan 3, Contamination count rate, 13-25 keV ct/s float nullable allc_flux 40-80 keV flux in ergs cm-2 s-1 keV-1 erg/cm^2/s/keV float nullable s3a_count_rate Scan 3, 13-25 keV count rate ct/s float nullable alla_flux 13-25 keV flux in ergs cm-2 s-1 keV-1 erg/cm^2/s/keV float nullable allcont_count_rate All data contamination count rate, 13-25 keV ct/s float nullable s3_start Start date of 3rd scan mjd double nullable s1c_count_rate_error Scan 1, 40-80 keV count rate error ct/s float nullable s2a_count_rate Scan 2, 13-25 keV count rate ct/s float nullable s1b_count_rate Scan 1, 25-40 keV count rate ct/s float nullable s2c_count_rate_error Scan 2, 40-80 keV count rate error ct/s float nullable s1d_count_rate Scan 1, 80-180 keV count rate ct/s float nullable s1b_count_rate_error Scan 1, 25-40 keV count rate error ct/s float nullable alld_flux 80-180 keV flux in ergs cm-2 s-1 keV-1 erg/cm^2/s/keV float nullable s2d_count_rate_error Scan 2, 80-180 keV count rate error ct/s float nullable allc_count_rate_error All data 40-80 keV count rate error ct/s float nullable opt_radio_name Optical or radio counterpart of object char nullable alld_flux_error 80-180 keV flux error erg/cm^2/s/keV float nullable alld_count_rate All data 80-180 keV count rate ct/s float nullable s2cont_count_rate Scan 2, Contamination count rate, 13-25 keV ct/s float nullable s3_end End date of 3rd scan mjd double nullable s2c_count_rate Scan 2, 40-80 keV count rate ct/s float nullable s3abc_count_rate Scan 3, 13-80 keV count rate ct/s float nullable s1a_count_rate_error Scan 1, 13-25 keV count rate error ct/s float nullable s1_start Start date of 1st scan mjd double nullable s3a_count_rate_error Scan 3, 13-25 keV count rate error ct/s float nullable s2b_count_rate_error Scan 2, 25-40 keV count rate error ct/s float nullable s1abc_count_rate_error Scan 1, 13-80 keV count rate error ct/s float nullable s1_end End date of 1st scan mjd double nullable allc_flux_error 40-80 keV flux error erg/cm^2/s/keV float nullable alla_count_rate All data 13-25 keV count rate ct/s float nullable allc_count_rate All data 40-80 keV count rate ct/s float nullable elat Ecliptic Latitude degree double nullable s2abc_count_rate Scan 2, 13-80 keV count rate ct/s float nullable s3c_count_rate_error Scan 3, 40-80 keV count rate error ct/s float nullable allb_flux_error 25-40 keV flux error erg/cm^2/s/keV float nullable s3d_count_rate_error Scan 3, 80-180 keV count rate error ct/s float nullable elong Ecliptic Longitude degree double nullable s3c_count_rate Scan 3, 40-80 keV count rate ct/s float nullable alla_flux_error 13-25 keV flux error erg/cm^2/s/keV float nullable s1abc_count_rate Scan 1, 13-80 keV count rate ct/s float nullable s3b_count_rate Scan 3, 25-40 keV count rate ct/s float nullable s2d_count_rate Scan 2, 80-180 keV count rate ct/s float nullable s3d_count_rate Scan 3, 80-180 keV count rate ct/s float nullable