J/ApJS/269/7ivo://CDS.VizieR/J/ApJS/269/7doi:10.26093/cds/vizier.22690007CDSWright N.J.Drake J.J.Guarcello M.G.Aldcroft T.L.Kashyap V.L.,Damiani F.DePasquale J.Fruscione A.2023-12-14T01:26:13Z2023-11-08T09:26:40ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frstellar-associationsx-ray-sourcesThe Cygnus OB2 association is the largest concentration of young and massive stars within 2kpc of the Sun, including an estimated 65 O-type stars and hundreds of OB stars. The Chandra Cygnus OB2 Legacy Survey is a large imaging program undertaken with the Advanced CCD Imaging Spectrometer onboard the Chandra X-ray Observatory. The survey has imaged the central 0.5deg^2^ of the Cyg OB2 association with an effective exposure of 120ks and an outer 0.35 deg^2^ area with an exposure of 60ks. Here we describe the survey design and observations, the data reduction and source detection, and present a catalog of 8,000 X-ray point sources. The survey design employs a grid of 36 heavily (~50%) overlapping pointings, a method that overcomes Chandra's low off-axis sensitivity and produces a highly uniform exposure over the inner 0.5deg^2^. The full X-ray catalog is described here and is made available online.2023ApJS..269....7Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/269/7CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/149/123 : WSRT survey of Cygnus OB2 (Setia Gunawan+, 2003)J/A+A/464/211 : Chandra & near-IR obs. of Cyg OB2 (Albacete Colombo+, 2007)J/A+A/472/557 : Cygnus OB2 region 610MHz sources (Marti+, 2007)J/A+A/474/495 : X-ray flares from Cygnus OB2 young starsJ/ApJS/184/84 : X-ray sources in Cyg OB2 region (Wright+, 2009)J/MNRAS/460/2593 : Cygnus OB2 DANCe: Proper motion study (Wright+, 2016)J/MNRAS/502/6080 : New members of Cygnus OB2 from Gaia DR2 (Orellana+, 2021)J/A+A/637/A64 : Cygnus OB2 e-MERLIN 21cm survey (COBRaS) (Morford+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/269/7https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/269/7http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/269/7https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/269/7https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/269/7http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/269/7GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/269/7/table2 (Chandra Cygnus OB2 Legacy Survey Catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/269/7/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/269/7/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/269/7/table2?GETtext/xml+votable180.050000true307.5313441.467568060.0055555555555555566/14670-14671 14692-14694https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/269/7?format=asciiX-raydefaultJ/ApJS/269/7/table2Chandra Cygnus OB2 Legacy Survey CatalogrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNumber[1/7924] X-ray source number within the Chandra Cygnus OB2 Legacy Surveymeta.idintNameIAU source name, CXOCOB2 JHHMMSS.ss+DDMMSS.smeta.id;meta.maincharRAJ2000Right ascension (J2000.0)degpos.eq.ra;meta.mainDEJ2000Declination (J2000.0)degpos.eq.dec;meta.mainPosErr1 sigma error circle around source positionarcsecstat.errorfloatSusFlag[0] Flag indicating the source is close to known PSF feature (2)meta.codeintSignifSource significance (from full band)stat.fit.goodnessfloatPrbNoSrcBase 10 logarithm of the p-value for no-source null hypothesisstat.fit.goodnessfloatDetMeth[0/5] Method used for detecting the candidate source (4)meta.codeintExpTmTotTotal exposure time in all observationsstime.duration;obsdoubleExpTmNomExposure time in all merged observations used for photometrysinstr.setup;obsdoubleExpTmFraFration of ExpTmTot used for photometrytime.expofloatNumObTotTotal number of observations of the sourcemeta.numberintNumObNomNumber of observations of the source merged for photometrymeta.numberintb_ThetaSmallest off-axis angle for merged observationsarcmininstr.offsetfloatThetaAverage off-axis angle for merged observationsarcmininstr.offsetfloatB_ThetaLargest off-axis angle for merged observationsarcmininstr.offset;stat.maxfloatPSFFracAverage PSF fraction (at 1.5keV) for merged observationsinstr.det.psffloatSrcAreaAverage aperture area for merged observationspixel**2phys.angSize;instr.fovintProbKSsSmallest p-value for the non-variable null hypothesis from a single observationstat.fit.goodnessfloatProbKSmSmallest p-value for the non-variable null hypothesis from all merged observationsstat.fit.goodnessfloatSCntFullObserved counts in merged source apertures (full band)ctphot.count;em.X-rayintSCntSoftObserved counts in merged source apertures (soft band)ctphot.count;em.X-rayintSCntHardObserved counts in merged source apertures (hard band)ctphot.count;em.X-rayintBCntFullObserved counts in merged background regions (full band)ctphot.count;em.X-rayintBCntSoftObserved counts in merged background regions (soft band)ctphot.count;em.X-rayintBCntHardObserved counts in merged background regions (hard band)ctphot.count;em.X-rayintBkgScaleScaling of the background extraction regioninstr.backgroundfloatNCntFullNet counts in merged source apertures (full band)ctphot.count;em.X-raydoubleNCntSoftNet counts in merged source apertures (soft band)ctphot.count;em.X-raydoubleNCntHardNet counts in merged source apertures (hard band)ctphot.count;em.X-raydoubleARFFullMean ARF value (full band) (in erg/cm2/ph) (5)1e-07J.cm**-2.ph**-1stat.value;stat.meanfloatARFSoftMean ARF value (soft band) (in erg/cm2/ph) (5)1e-07J.cm**-2.ph**-1stat.value;stat.meanfloatARFHardMean ARF value (hard band) (in erg/cm2/ph) (5)1e-07J.cm**-2.ph**-1stat.value;stat.meanfloatMedEFullMedian energy of the observed spectrum (full band)keVem.energyfloatMedESoft? Median energy of the observed spectrum (soft band)keVem.energyfloatnullableMedEHard? Median energy of the observed spectrum (hard band)keVem.energyfloatnullableFluxFullEnergy flux of the observed spectrum (full band) (in erg/cm2/s)mW.m**-2phot.flux;em.X-raydoubleFluxSoft? Energy flux of the observed spectrum (soft band) (in erg/cm2/s)mW.m**-2phot.flux;em.X-raydoublenullableFluxHard? Energy flux of the observed spectrum (hard band) (in erg/cm2/s)mW.m**-2phot.flux;em.X-raydoublenullableb_NCntFull1 sigma lower bound on NCntFullctstat.stdev;stat.mindoubleB_NCntFull1 sigma upper bound on NCntFullctstat.stdev;stat.maxdoubleb_NCntSoft? 1 sigma lower bound on NCntSoftctstat.stdev;stat.mindoublenullableB_NCntSoft1 sigma upper bound on NCntSoftctstat.stdev;stat.maxdoubleb_NCntHard? 1 sigma lower bound on NCntHardctstat.stdev;stat.mindoublenullableB_NCntHard1 sigma upper bound on NCntHardctstat.stdev;stat.maxdoublePosTypeMethod used to estimate source position (1)meta.codecharPrbBandBand used for PrbNoSrc (3)instr.bandpasschar