Chan/Seren/ID ivo://nasa.heasarc/chansexsi NASA/GSFC HEASARC Harrison et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The Serendipitous Extragalactic X-Ray Source Identification (SEXSI) program is designed to extend greatly the sample of identified extragalactic hard X-ray (2 - 10 keV) sources at intermediate fluxes (~10<sup>-13</sup> to 10<sup>-15</sup> erg/cm<sup>2</sup>/s). SEXSI, which studies sources selected from more than 2 deg<sup>2</sup>, provides an essential complement to the Chandra Deep Fields, which reach depths of 5 x 10<sup>-16</sup> erg/cm<sup>2</sup>/s (2 - 10 keV) but over a total area of less than 0.2 deg<sup>2</sup>. In their published paper, the authors describe the characteristics of the survey and their X-ray data analysis methodology. They present the cumulative flux distribution for the X-ray sample of 1034 hard sources and discuss the distribution of spectral hardness ratios. Their log N -log S in this intermediate flux range connects to those found in the Deep Fields, and by combining the data sets, they constrain the hard X-ray population over the flux range in which the differential number counts change slope and from which the bulk of the 2 - 10 keV X-ray background arises. They further investigate the log N - log S distribution separately for soft and hard sources in the sample, finding that while a clear change in slope is seen for the softer sample, the hardest sources are well described by a single power law down to the faintest fluxes, consistent with the notion that they lie at lower average redshift. In the SEXSI program, fields were selected with high Galactic latitude (|b| > 20 degrees) and with declinations accessible to the optical facilities available to the authors (declination > -20 degrees). They used observations taken with Chandra's Advanced Camera for Imaging Spectroscopy (ACIS I- and S-modes; Bautz et al., 1998, Proc. SPIE, 3444, 210) only (for sensitivity in the hard band). All the fields presented in this paper have data that are available in the Chandra public archive. This table was created by the HEASARC in June 2004 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/596/944/table4.dat">CDS Catalog J/ApJ/596/944/table4.dat</a> which is a representation of Table 4 from the published paper. Note that it does not include the Soft-Band-Only Source Catalog (Table 6 in the published version of the paper). This is a service provided by NASA HEASARC . 2003ApJ...596..944H https://heasarc.gsfc.nasa.gov/W3Browse/all/chansexsi.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=chansexsi& GET text/xml 180 99999 true 193.20941667 -9.40458333 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=chansexsi GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_chansexsi&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public chansexsi Chandra Serendipitous Extragalactic X-Ray Source ID (SEXSI) Cata name Object Designation (CXOSEXSI JHHMMSS.s+DDMMSS) meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable hb_counts Background-Subtracted Hard-Band (2.1-7 keV) Counts ct phot;em.X-ray.medium double nullable hb_counts_snr Signal-to-Noise Ratio of the Hard-Band Detection stat.snr;phot;em.X-ray.medium double nullable hb_flux Unabsorbed Hard-Band (2.0-10 keV) Flux (erg/cm^2/s) erg/s/cm^2 phot.flux;em.X-ray.medium double nullable sb_flux Unabsorbed Soft-Band (0.5-2.0 keV) Flux (erg/cm^2/s) erg/s/cm^2 phot.flux;em.X-ray.soft double nullable bii Galactic Latitude degree pos.galactic.lat double nullable sb_counts_snr Signal-to-Noise Ratio of the Soft-Band Detection stat.snr;phot;em.X-ray.soft double nullable hb_bck_counts Estimated Background Counts within Hard Counts Extraction Aperture ct instr.background;phot;em.X-ray.medium double nullable sb_bck_counts Estimated Background Counts within Soft Counts Extraction Aperture ct instr.background;phot;em.X-ray.soft double nullable hardness_ratio Hardness Ratio phot.count;arith.ratio;em.X-ray.medium double nullable sb_counts Background-Subtracted Soft-Band (0.3-2.1 keV) Counts ct phot;em.X-ray.soft double nullable off_axis_angle Off-Axis Angle (arcmin) arcmin instr.offset double nullable lii Galactic Longitude degree pos.galactic.lon double nullable cluster_flag Flag Indicates Whether Source Falls within 1 Mpc of a Cluster Center meta.code;src short 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