J/ApJ/577/738ivo://CDS.VizieR/J/ApJ/577/738doi:10.26093/cds/vizier.15770738CDSKong A.K.H.Garcia M.R.Primini F.A.Murray S.S.di Stefano R.,McClintock J.E.2003-08-22T13:46:24Z2003-08-22T13:46:16ZCDS support team

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

cds-question@unistra.frgalaxiesx-ray-sourcesWe report on Chandra observations of the central region of M31. By combining eight Chandra ACIS-I observations taken between 1999 and 2001, we have identified 204 X-ray sources within the central ~17'x17' region of M31, with a detection limit of ~2x10^35^erg/s. Of these 204 sources, 22 are identified with globular clusters, two with supernova remnants, nine with planetary nebulae, and nine with supersoft sources. By comparing individual images, about 50% of the sources are variable on timescales of months. We also found 13 transients, with light curves showing a variety of shapes. We also extracted the energy spectra of the 20 brightest sources; they can be well fitted by a single power law with a mean photon index of 1.8. The spectral shapes of 12 sources are shown to be variable, suggesting that they went through state changes.2002ApJ...577..738Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/577/738CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 2002)J/ApJ/578/114 : Chandra HRC source in M31 (Kaaret, 2002)II/144 : Brightest stars in the field of M31 (Berkhuijsen+ 1988)J/A+A/373/63 : M31 second ROSAT PSPC survey (Supper+, 2001)J/A+AS/61/451 : The 37W catalogue of radio sources in M31 (Walterbos+ 1985)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/577/738https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/577/738http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/577/738https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/577/738https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/577/738http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/577/738GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/577/738/table2 (CHANDRA ACIS catalog of the central region of M31)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/577/738/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/577/738/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/577/738/table2?GETtext/xml+votable180.050000true10.4597333341.226988890.0055555555555555566/2623 2709https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/577/738?format=asciiX-raydefaultJ/ApJ/577/738/table2CHANDRA ACIS catalog of the central region of M31e_HR2The error in HR2stat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[KGP2002]Object identificationmeta.id;meta.maincharprimaryCXOM31Chandra name (JHHMMSS.s+DDMMSS)meta.idcharRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainPosErrPositional errorarcsecstat.errorfloatNCtsThe net countsctphot.count;em.X-rayintCRateThe count rate in units of 10^-2^ct/s0.01count.s**-1phot.count;em.X-rayfloate_CRateError in CRate0.01count.s**-1stat.errorfloatHR1The first hardness ratio (1)phot.flux;arith.ratiofloate_HR1The error in HR1stat.errorfloatHR2The second hardness ratio (2)phot.flux;arith.ratiofloatLXrayThe 0.3-7keV luminosity in units of 10^37^erg/s (3)1e+30Wphys.luminosity;em.X-rayfloatNotesAdditional notes (4)meta.notecharJ/ApJ/577/738/table4Optical IDsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[KGP2002]Object identificationmeta.id;meta.maincharCXOM31Chandra Name (JHHMMSS.s+DDMMSS)meta.idcharMTypeMorphological typesrc.morph.typecharIdentIdentification (1)meta.id.crosscharOffRadial offset between the catalogued object and the ACIS sourcearcsecpos.angDistancefloatIdent2Second identification (1)meta.id.crosscharOff2? Radial offset between the catalogued object and the ACIS sourcearcsecpos.angDistancefloatnullableJ/ApJ/577/738/table5Cross-Correlation of Chandra and ROSAT SourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[KGP2002]Object Identificationmeta.id;meta.maincharCXOM31Chandra name (JHHMMSS.s+DDMMSS)meta.idchar[PFJ93]? ROSAT HRI Identification (Primini et al., 1993ApJ...410..615Pmeta.idintnullableOffRadial offset between the HRI and ACIS objectsarcsecpos.angDistancefloat