CYGOB2CXO2 ivo://nasa.heasarc/cygob2cxo2 NASA/GSFC HEASARC Wright, Drake 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains a catalog of 1696 X-ray sources detected in the massive star-forming region (SFR) Cygnus OB2 and extracted from two archival Chandra observations of the center of the region. A deep source extraction routine, exploiting the low background rates of Chandra observations was employed to maximize the number of sources extracted. Observations at other wavelengths were used to identify low count-rate sources and remove likely spurious sources. Monte Carlo simulations were also used to assess the authenticity of these sources. X-ray spectra were fitted with thermal plasma models to characterize the objects and X-ray light curves were analyzed to determine their variability. The authors used a Bayesian technique to identify optical or near-IR counterparts for 1501 (89%) of our sources, using deep observations from the INT Photometric H-alpha Survey, the Two Micron All Sky Survey (2MASS), and the UKIRT Infrared Deep Sky Survey-Galactic Plane Survey. 755 (45%) of these objects have six-band r&#39;, H-alpha, i&#39;, J, H, and K optical and near-IR photometry. From an analysis of the Poisson false-source probabilities for each source they estimate that their X-ray catalog includes &lt;1% of false sources, and an even lower fraction when only sources with optical or near-IR associations are considered. A Monte Carlo simulation of the Bayesian matching scheme allows this method to be compared to more simplified matching techniques and enables the various sources of error to be quantified. The catalog of 1696 objects presented here includes X-ray broad-band fluxes, spectral model fits, and optical and near-IR photometry in what is one of the largest X-ray catalogs of a single SFR to date. The high number of stellar X-ray sources detected from relatively shallow observations confirms the status and importance of Cygnus OB2 as one of our Galaxy&#39;s most massive SFRs. This table was created by the HEASARC in October 2009 based on electronic versions of Tables 2, 3 and 4 from the reference paper which were obtained from the CDS (their catalog J/ApJS/184/84 files table2.dat, table3.dat and table4.dat). This is a service provided by NASA HEASARC . 2009ApJS..184...84W https://heasarc.gsfc.nasa.gov/W3Browse/all/cygob2cxo2.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=cygob2cxo2& GET text/xml 180 99999 true 308.44620833 41.07922222 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=cygob2cxo2 GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_cygob2cxo2&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 Infrared X-ray public cygob2cxo2 Cygnus OB2 Association Chandra X-Ray Point Source Catalog 2 name Source Designation 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 counts Net 0.5-8keV Band Counts ct phot;em.X-ray double nullable counts_neg_err Lower 1-Sigma Error on Net 0.5-8keV Band Counts ct stat.error;phot;em.X-ray double nullable counts_pos_err Upper 1-Sigma Error on Net 0.5-8keV Band Counts ct stat.error;phot;em.X-ray double nullable log_lx Logarithm 0.5-8keV Band Luminosity log(erg/s) phys.luminosity;em.X-ray double nullable log_lx_neg_err Lower 90%-Confidence Interval in Log_Lx log(erg/s) stat.error;phys.luminosity;em.X-ray double nullable log_lx_pos_err Upper 90%-Confidence Interval in Log_Lx log(erg/s) stat.error;phys.luminosity;em.X-ray double nullable jmag The J Band Magnitude mag phot.mag;em.IR.J 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 median_energy The 0.5-8keV Median Energy keV phys.energy double nullable psf_fraction Point Spread Function Fraction in Extraction Region instr.det.psf double nullable twomass_flags 2MASS Photometric Quality Flags meta.code;src char nullable rmag IPHAS r-prime Band Magnitude mag phot.mag;em.opt.R double nullable exposure Full Exposure Time (s) s time.duration;obs.exposure double nullable apec_kt_neg_err Lower 90%-Confidence Interval in kT keV stat.error;phys.temperature double nullable class Browse Object Classification src.class short nullable extraction_area Source Extraction Region Area (pixels) pixel instr.det.psf short nullable log_sb_lx Logarithm 0.5-2keV Band Luminosity log(erg/s) phys.luminosity;em.X-ray.soft double nullable ra_oir Right Ascension of Optical/Infrared Source degree meta.id.assoc;pos.eq.ra double nullable jmag_error Error in Jmag mag stat.error;phot.mag;em.IR.J double nullable log_prob_constant Logarithm of Kolmogorov-Smirnov Probability stat.probability double nullable apec_kt_limit Limit Flag for kT meta.code;phys.temperature char nullable log_nh_pos_err Upper 90%-Confidence Interval in Logarithm of Hydrogen Column Density log(cm^-2) stat.error;phys.columnDensity double nullable snr Source Detection Significance stat.snr;em.X-ray double nullable halpha_mag_error Error in H-alpha Band Magnitude mag stat.error;phot.mag;em.line.Halpha double nullable opt_name Optical Source Designation meta.id.assoc char nullable alt_name Alternative Catalog-Based Source Designation meta.id char nullable imag_error Error in IPHAS i-prime Band Magnitude mag stat.error;phot.mag;em.opt.I double nullable near_ir_flags Near-IR Photometry Source Flag meta.code;em.IR char nullable ks_mag The Ks Band Magnitude mag phot.mag;em.IR.K double nullable nh_limit Limit Flag for Logarithm of Hydrogen Column Density meta.code;phys.columnDensity char nullable dec_oir Declination of Optical/Infrared Source degree meta.id.assoc;pos.eq.dec double nullable halpha_mag IPHAS H-alpha Band Magnitude mag phot.mag;em.line.Halpha double nullable count_rate Net 0.5-8keV Band Count Rate ct/s phot.count;em.X-ray double nullable log_bck_prob Logarithm of Poisson Probability stat.probability double nullable hmag_error Error in Hmag mag stat.error;phot.mag;em.IR.H double nullable sb_count_rate Net 0.2-2keV Band Count Rate ct/s phot.count;em.X-ray.soft double nullable lii Galactic Longitude degree pos.galactic.lon double nullable log_nh_neg_err Lower 90%-Confidence Interval in Logarithm of Hydrogen Column Density log(cm^-2) stat.error;phys.columnDensity double nullable hb_count_rate Net 2-8keV Band Count Rate ct/s phot.count;em.X-ray.medium double nullable log_hb_lx Logarithm 2-8keV Band Luminosity log(erg/s) phys.luminosity;em.X-ray.medium double nullable afm2007_source_number Albacete Colombo et al. (2007, Cat. <J/A+A/464/211>) Catalog Number meta.id.assoc short nullable hmag The J Band Magnitude mag phot.mag;em.IR.H double nullable apec_kt Model Fit Thermal Plasma Temperature keV phys.temperature double nullable field_number Source Field Number [1-3] meta.id;obs.field short nullable spectral_model Model Fit Type meta.code;spect;meta.modelled char nullable bii Galactic Latitude degree pos.galactic.lat double nullable spect_type Literature MK Spectral Type src.spType char nullable off_set X-Ray and Optical/NIR Position Offset (arcsec) arcsec pos.angDistance double nullable ks_mag_error Error in Ks_mag mag stat.error;phot.mag;em.IR.K double nullable source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable imag IPHAS i-prime Band Magnitude mag phot.mag;em.opt.I double nullable apec_kt_pos_err Upper 90%-Confidence Interval in kT keV stat.error;phys.temperature double nullable off_axis Off-Axis Angle (arcmin) arcmin instr.offset double nullable log_nh Logarithm of Hydrogen Column Density log(cm^-2) phys.columnDensity double nullable source_flag Flag [EN] Indicates Warning meta.code char nullable rmag_error Error in IPHAS r-prime Band Magnitude mag stat.error;phot.mag;em.opt.R double nullable ref_spect_type Reference for MK Spectral Type meta.ref;src.spType char nullable