XMMSSCLWBS ivo://nasa.heasarc/xmmssclwbs NASA/GSFC HEASARC Lin et al. 2026-07-17 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The authors have carried out a classification of 4,330 X-ray sources in the 2XMMi-DR3 catalog. The sources were selected under the requirement of being a point source with multiple XMM-Newton observations and at least one detection with a signal-to-noise ratio larger than 20. For about one-third of the sources, the authors are able to obtain reliable source types from the literature. They mostly correspond to various types of stars (611), active galactic nuclei (AGNs, 753), and compact object systems (138) containing white dwarfs, neutron stars, and stellar-mass black holes. The authors find that about 99% of stars can be separated from other source types based on their low X-ray-to-IR flux ratios and frequent X-ray flares. AGNs have remarkably similar X-ray spectra, with the power-law photon index centered around 1.91 +/- 0.31, and their 0.2-4.5 keV flux long-term variation factors have a median of 1.48, with 98.5% being less than 10. In contrast, 70% of compact object systems can be very soft or hard, highly variable in X-rays, and/or have very large X-ray-to-IR flux ratios, separating them from AGNs. Using these results, the authors derive a source type classification scheme to classify the other sources and find 644 candidate stars, 1,376 candidate AGNs, and 202 candidate compact object systems, whose false identification probabilities are estimated to be about 1%, 3%, and 18%, respectively. There are still 320 sources associated with nearby galaxies and 151 in the Galactic plane, which the authors expect to be mostly compact object systems or background AGNs. There are also 100 candidate ultraluminous X-ray sources. They are found to be much less variable than other accreting compact objects. This table was created by the HEASARC in October 2012 based on an electronic version of Table 4 from the reference paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC . 2012ApJ...756...27L https://heasarc.gsfc.nasa.gov/W3Browse/all/xmmssclwbs.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=xmmssclwbs& GET text/xml 180 99999 true 46.55523 -78.04514 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=xmmssclwbs GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_xmmssclwbs&Action=More+Options&Action=Parameter+Search&ConeAdd=1 XMM-NEWTON 0.0166666666666667 Optical X-ray public xmmssclwbs XMM-Newton 2XMMi-DR3 Selected Source Classifications Catalog name 2XMMi-DR3 Source Designation meta.id;meta.main char nullable srcid Unique Source Identifier meta.id;src int nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable object_type Source Type src.class char nullable r1_mag R1 Magnitude mag phot.mag;em.opt.R double nullable jmag 2MASS J Magnitude (1.2-Micron) mag phot.mag;em.IR.J double nullable log_fx_fo Logarithm of the X-Ray-to-Optical Flux Ratio phot.flux;arith.ratio;em.X-ray;em.opt double nullable flux_var_factor_8 Flux Variation Factor in 0.2-12.0keV Band phot.flux;arith.ratio;em.X-ray double 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 obsid_min_flux_1234 Corresponding Observation Identification of Minimum Flux in 0.2-4.5keV Band meta.id;obs char nullable time_span_observations Time Span of All Observations d time.duration double nullable jmag_error Mean Error on J Magnitude mag stat.error;phot.mag;em.IR.J double nullable rc3_dec Declination from RC3 or NED degree pos.eq.dec double nullable max_flux_8_error Uncertainty in Maximum Flux in 0.2-12.0keV Band erg/s/cm^2 stat.error;phot.flux;em.X-ray double nullable imag I Magnitude mag phot.mag;em.opt.I double nullable sig_var_factor_8 Significance of Flux Variation stat.param;src.var double nullable time_span_detections Time Span of All Detections from 2XMMi-DR3 Catalog d time.duration double nullable max_flux_1234 Maximum Flux in 0.2-4.5keV Band erg/s/cm^2 phot.flux;em.X-ray double nullable xmm_usnob1_offset Angular Separation Between the X-Ray Position and USNO-B1.0 Source arcsec pos.angDistance;em.X-ray;em.opt double nullable min_flux_8_error Uncertainty in Minimum Flux in 0.2-12.0keV Band erg/s/cm^2 stat.error;phot.flux;em.X-ray double nullable error_radius Mean Error on Position arcsec stat.error;pos double nullable obsid_max_flux_8 Corresponding Observation Identification of Maximum Flux in 0.2-12.0keV Band meta.id;obs char nullable obsid_min_flux_8 Corresponding Observation Identification of Minimum Flux in 0.2-12.0keV Band meta.id;obs char nullable b2_mag B2 Magnitude mag phot.mag;em.opt.B double nullable hmag_error Mean Error on H Magnitude mag stat.error;phot.mag;em.IR.H double nullable num_observations Number of Observations meta.number;obs short nullable b1_mag B1 Magnitude mag phot.mag;em.opt.B double nullable twomass_name 2MASS PSC Source Designation meta.id.cross char nullable obsid_max_flux_1234 Corresponding Observation Identification of Maximum Flux in 0.2-4.5keV Band meta.id;obs char nullable alt_object_type Spectral Type in the Reference src.class char nullable xmm_twomass_offset Angular Separation Between the X-Ray Position and 2MASS PSC Source arcsec pos.angDistance;em.X-ray;em.IR double nullable qual_usnob1_match 1 If the Optical Match Is Bad meta.code.qual short nullable hmag 2MASS H Magnitude (1.6-Micron) mag phot.mag;em.IR.H double nullable co_class_reasons Reasons for Classifying It As a Compact Object System meta.code;src.class char nullable min_flux_1234 Minimum Flux in 0.2-4.5keV Band erg/s/cm^2 phot.flux;em.X-ray double nullable object_type_rel Category of Source Type: A=identified, B=candidate meta.code.qual;src.class char nullable num_detections Number of Detections from 2XMMi-DR3 Catalog meta.number;obs short nullable ref_object_type Reference, Mostly on the Source Type meta.ref;src.class char nullable xmm_rc3_offset Angular Separation from the RC3 Match arcsec pos.angDistance;em.X-ray;em.opt double nullable max_flare_bck_ratio Maximum Ratio of Flare Peak to Persistent Background phot.flux;arith.ratio;em.X-ray double nullable flux_var_factor_1234 Flux Variation Factor in 0.2-4.5keV Band phot.flux;arith.ratio;em.X-ray double nullable qual_twomass_match 1 If the IR match Is Bad meta.code.qual short nullable galaxy_distance Distance to the Galaxy Mpc pos.distance double nullable ks_mag 2MASS Ks Magnitude (2.2-Micron) mag phot.mag;em.IR.K double nullable bii Galactic Latitude degree pos.galactic.lat double nullable nh_gal Leiden/Argentine/Bonn Survey of Galactic HI Column Density cm^-2 phys.columnDensity double nullable max_flux_8 Maximum Flux in 0.2-12.0keV Band erg/s/cm^2 phot.flux;em.X-ray double nullable max_flux_1234_error Uncertainty in Maximum Flux in 0.2-4.5keV Band erg/s/cm^2 stat.error;phot.flux;em.X-ray double nullable r2_mag R2 Magnitude mag phot.mag;em.opt.R double nullable alt_name Source Designation in the Reference meta.id char nullable min_flux_8 Minimum Flux in 0.2-12.0keV Band erg/s/cm^2 phot.flux;em.X-ray double nullable lx_max Maximum 0.2-12.0 keV Luminosity erg/s phys.luminosity;em.X-ray double nullable rc3_ra Right Ascension from RC3 or NED degree pos.eq.ra double nullable min_flux_1234_error Uncertainty in Minimum Flux in 0.2-4.5keV Band erg/s/cm^2 stat.error;phot.flux;em.X-ray double nullable lii Galactic Longitude degree pos.galactic.lon double nullable class Browse Object Classification src.class short nullable xmm_rc3_offset_d25 Ratio of Angular Separation to D25 Isophote Elliptical Radius pos.angDistance;arith.ratio double nullable usnob1_name USNO-B1.0 Source Designation meta.id.cross char nullable rc3_galaxy_name RC3 Galaxy Designation meta.id.cross char nullable log_fx_fir Logarithm of the X-Ray-to-IR Flux Ratio phot.flux;arith.ratio;em.X-ray;em.IR double nullable obsid_flare Corresponding Observation Identification of the Flare meta.id;obs int nullable sig_var_factor_1234 Significance of Flux Variation stat.param;src.var double nullable ks_mag_error Mean Error on Ks Magnitude mag stat.error;phot.mag;em.IR.K double nullable