J/ApJS/209/9ivo://CDS.VizieR/J/ApJS/209/9doi:10.26093/cds/vizier.22090009CDSPaggi A.Massaro F.D'Abrusco R.Smith H.A.Masetti N.Giroletti M.,Tosti G.Funk S.2017-07-06T06:25:59Z2013-12-13T12:04:41ZCDS support team

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

cds-question@unistra.frgamma-ray-astronomyastronomical-object-identificationx-ray-sourcesinfrared-photometryvisible-astronomybroad-band-photometryultraviolet-photometrybl-lacertae-objectsA significant fraction (~30%) of the high-energy {gamma}-ray sources listed in the second Fermi Large Area Telescope (LAT) catalog are still of unknown origin, having not yet been associated with counterparts at lower energies. To investigate the nature of these enigmatic sources, we present an extensive search of X-ray sources lying in the positional uncertainty region of a selected sample of these unidentified gamma-ray sources (UGSs) that makes use of all available observations performed by the Swift X-ray Telescope before 2013 March 31, available for 205 UGSs. To detect the fainter sources, we merged all the observations covering the Fermi LAT positional uncertainty region at a 95% level of confidence of each UGS. This yields a catalog of 357 X-ray sources, finding candidate X-ray counterparts for ~70% of the selected sample. In particular, 25% of the UGSs feature a single X-ray source within their positional uncertainty region, while 45% have multiple X-ray sources. For each X-ray source, we also looked in the corresponding Swift UVOT merged images for optical and ultraviolet counterparts, also performing source photometry. We found ultraviolet-optical correspondences for ~70% of the X-ray sources. We searched several major radio, infrared, optical, and ultraviolet surveys for possible counterparts within the positional error of the sources in the X-ray catalog to obtain additional information on their nature. Applying the kernel density estimation technique to infrared colors of Wide-Field Infrared Survey Explorer counterparts of our X-ray sources we select six {gamma}-ray blazar candidates. In addition, comparing our results with previous analyses, we select 11 additional {gamma}-ray blazar candidates.2013ApJS..209....9Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/209/9CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/284 : The USNO-B1.0 Catalog (Monet+ 2003)J/ApJS/209/10 : Unidentified {gamma}-ray sources. V. (Massaro+, 2013)J/ApJS/208/25 : Swift X-ray observations of 1FGL sources (Takeuchi+, 2013)J/ApJS/207/16 : BL Lac candidates for TeV observations (Massaro+, 2013)J/ApJS/207/4 : Unidentified {gamma}-ray sources. III. Radio (Massaro+, 2013)J/ApJS/206/17 : New gamma-ray blazar candidates in the 3PBC (Maselli+, 2013)J/ApJS/206/13 : Blazars with {gamma}-ray counterparts. II. (Massaro+, 2013)J/ApJS/206/12 : Blazars with {gamma}-ray counterparts. I. (D'Abrusco+, 2013)J/A+A/551/A142 : 7 year Swift-XRT point source catalog (1SWXRT) (D'Elia+, 2013)J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)J/A+A/541/A160 : X & gamma-ray observations of selected blazars (Giommi+, 2012)J/ApJ/742/66 : New Fermi/LAT extragalactic sources (Teng+, 2011)J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)J/ApJ/709/1407 : SED of the Fermi blazars (Li+, 2010)J/MNRAS/403/945 : Swift/XRT obs. of unidentified IBIS sources (Landi+, 2010)J/A+A/458/245 : Obs. of 2 Unidentified Gamma-ray Sources (La Palombara+, 2006)J/A+A/379/755 : Radio data of X- and gamma-ray loud blazars (Venturi+, 2001)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/209/9https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/209/9http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/209/9https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/209/9https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/209/9http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/209/9GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/209/9/swift (Catalog of XRT-PC detected in the positional uncertainty region of the 2FGL source with their UVOT counterparts)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/209/9/swift?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/209/9/swift?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/209/9/swift?GETtext/xml+votable180.050000true7.728404177.390091670.005555555555555556Cone search capability for table J/ApJS/209/9/table3 (XRT-PC sources featuring a USNO-B counterpart within the positional error)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/209/9/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/209/9/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/209/9/table3?GETtext/xml+votable180.050000true7.7283337.390.0055555555555555566/172 189 267 289 720 731 813 2754 2755 3234 3336 3338 3441 3871 5346 5352 5448 5450 6292 7131 7767 7936 7937 8091 9175 9417 9821 9855 11457 12207 12277 12410 12782 12783 13279 14263 14656 14658 14712 15407 15677 15783 15996 17341 18341 18343 18366 18444 19334 19421 19525 21010 21164 21593 21710 21806 21898 22237 22239 22683 22849 23105 23338 23982 24471 24564 24566 24836 24885 25140 25142 25468 25820 26892 28754 28805 29758 29881 30196 30957 31011 31092 31093 31111 31116 31221 31223 31856 31976 32249 32288 32628 32629 32737 32739 33028 33030 33059 33087 33173 33198 33464 33506 33528 34592 34593 35063 35227 36144 36615 36910 37183 37222 37487 37623 37886 37931 37991 38112 38482 38488 38511 38873 38911 39111 39733 39889 40113 40143 40680 41510 41516 41574 41735 41741 41837 41964 42150 42311 42744 43194 43228 43280 43435 43544 43643 43660 43877 43879 43905 44241 44540 44654 45316 45446 45496 45740 45741 46568 46720 46721 47154 47155 47442 47461 48528 48685 487733.377399441402775e-19 1.2058628298368645e-18https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/209/9?format=asciiGamma-rayX-rayUVOpticalInfrareddefaultJ/ApJS/209/9/swiftCatalog of XRT-PC detected in the positional uncertainty region of the 2FGL source with their UVOT counterpartsf_M2mag[*] * = filter saturationmeta.codecharE(B-V)[0.01/16] Galactic extinction (4)magphot.color.excessfloatExpV? UVOT V band exposure timestime.duration;obs.exposure;em.opt.VintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2FGL2nd Fermi LAT catalog ID (JHHMM.m+DDMM)meta.id;meta.maincharSwiftSwift/XRT source ID (JHHMMSS.s+DDMMSS)meta.id.crosscharprimaryMSimbad column added by the CDSmeta.ref.urlcharONameOther source name (1)meta.idcharRAJ2000XRT Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000XRT Degree of Declination (J2000)pos.eq.dec;meta.mainePos[3.5/9.1] Position errorarcsecstat.error;posfloatExpXRT-PC exposure timestime.duration;obs.exposureintD-CRCount rate by DETECTct/ksphot.count;em.X-rayfloate_D-CRUncertainty in D-CRct/ksstat.errorfloatSig[2/5] Signal-to-noise threshold above which source is detectedstat.likelihood;obsintS-CRCount rate by OSTAct/ksphot.count;em.X-rayfloate_S-CRUncertainty in S-CRct/ksstat.errorfloatSNR[0.22/91.12] Signal-to-Noisestat.snrfloatXcatList of catalogs cross-matched (2)meta.id;meta.datasetcharBlaz{gamma}-ray blazar-like source (3)meta.codecharz[0.0061/1.725]? Redshift from literaturesrc.redshiftdoublenullableRAuhUVOT Hour of Right Ascension (J2000)hpos.eq.raRAumUVOT Minute of Right Ascension (J2000)minpos.eq.raRAusUVOT Second of Right Ascension (J2000)spos.eq.raDEu-UVOT Sign of the Declination (J2000)pos.eq.deccharDEudUVOT Degree of Declination (J2000)degpos.eq.decDEumUVOT Arcminute of Declination (J2000)arcminpos.eq.decDEusUVOT Arcsecond of Declination (J2000)arcsecpos.eq.decSep[0/6.5] Angular separation between X-ray and UV sourcesarcsecpos.angDistancefloatVmag[11.46/21.22]? Swift/UVOT V band Vega magnitude from UVOTSOURCE (5)magphot.mag;em.opt.Vfloatnullablef_Vmag[*] * = filter saturationmeta.codechare_Vmag? Uncertainty in Vmag (6)magstat.error;phot.mag;em.opt.VfloatnullableVmag2[11.87/18.58]? Swift/UVOT V band Vega magnitude from UVOTDETECT (5)magphot.mag;em.opt.Vfloatnullablee_Vmag2? Uncertainty in Vmag2 (6)magstat.error;phot.mag;em.opt.VfloatnullableExpB? UVOT B band exposure timestime.duration;obs.exposure;em.opt.BintnullableBmag[13.12/22.03]? Swift/UVOT B band Vega magnitude from UVOTSOURCE (5)magphot.mag;em.opt.Bfloatnullablee_Bmag? Uncertainty in Bmag (6)magstat.error;phot.mag;em.opt.BfloatnullableBmag2[13.31/19.24]? Swift/UVOT B band Vega magnitude from UVOTDETECT (5)magphot.mag;em.opt.Bfloatnullablee_Bmag2? Uncertainty in Bmag2 (6)magstat.error;phot.mag;em.opt.BfloatnullableExpU? UVOT U band exposure timestime.duration;obs.exposure;em.opt.UintnullableUmag[11.91/21.91]? Swift/UVOT U band Vega magnitude from UVOTSOURCE (5)magphot.mag;em.opt.Ufloatnullablef_Umag[*] * = filter saturationmeta.codechare_Umag? Uncertainty in Umag (6)magstat.error;phot.mag;em.opt.UfloatnullableUmag2[11.83/21.46]? Swift/UVOT U band Vega magnitude from UVOTDETECT (5)magphot.mag;em.opt.Ufloatnullablef_Umag2[*] * = filter saturationmeta.codechare_Umag2? Uncertainty in Umag2 (6)magstat.error;phot.mag;em.opt.UfloatnullableExpW1? Swift/UVOT W1 band exposure timestime.duration;obs.exposureintnullableW1mag[11.01/22.23]? Swift/UVOT UVW1 band Vega magnitude from UVOTSOURCE (5)magphot.mag;em.UVfloatnullablef_W1mag[*] * = filter saturationmeta.codechare_W1mag? Uncertainty in W1mag (6)magstat.error;phot.magfloatnullableW1mag2[10.95/21.74]? Swift/UVOT UVW1 band Vega magnitude from UVOTDETECT (5)magphot.mag;em.UVfloatnullablef_W1mag2[*] * = filter saturationmeta.codechare_W1mag2? Uncertainty in W1mag2 (6)magstat.error;phot.magfloatnullableExpM2? Swift/UVOT UVM2 band exposure timestime.duration;obs.exposureintnullableM2mag[10.42/22.56]? Swift/UVOT UVM2 band Vega magnitude from UVOTSOURCE (5)magphot.mag;em.UVfloatnullablee_M2mag? Uncertainty in M2mag (6)magstat.error;phot.mag;em.IR.4-8umfloatnullableM2mag2[10.36/21.95]? Swift/UVOT UVM2 band Vega magnitude from UVOTDETECT (5)magphot.mag;em.UVfloatnullablef_M2mag2[*] * = filter saturationmeta.codechare_M2mag2? Uncertainty in M2mag2 (6)magstat.error;phot.mag;em.IR.4-8umfloatnullableExpW2? UVOT W2 band exposure timestime.duration;obs.exposureintnullableW2mag[12.23/22.8]? Swift/UVOT UVW2 band Vega magnitude from UVOTSOURCE (5)magphot.mag;em.UVfloatnullablee_W2mag? Uncertainty in W2mag (6)magstat.error;phot.magfloatnullableW2mag2[12.25/22.47]? Swift/UVOT UVW2 band Vega magnitude from UVOTDETECT (5)magphot.mag;em.UVfloatnullablee_W2mag2? Uncertainty in W2mag2 (6)magstat.error;phot.magfloatnullableJ/ApJS/209/9/table3XRT-PC sources featuring a USNO-B counterpart within the positional errorrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSwiftSwift designation (JHHMMSS.s+DDMMSS)meta.id;meta.maincharB1mag[7.1/21.5]? USNO-B first epoch blue magnitudemagphot.mag;em.opt.BfloatnullableR1mag[6.6/20.4]? USNO-B first epoch red magnitudemagphot.mag;em.opt.RfloatnullableB2mag[7/22.7]? USNO-B 2nd epoch blue magnitudemagphot.mag;em.opt.BfloatnullableR2mag[6.6/21.5]? USNO-B 2nd epoch red magnitudemagphot.mag;em.opt.RfloatnullableImag[6/20]? USNO-B NIR magnitudemagphot.mag;em.opt.IfloatnullableUSNOCross-match with the USNO-B1 catalog (Cat. I/284) within 7"meta.ref.urlchar_RAPositions from Swift names (right ascension part)degpos.eq.ra;meta.main_DEPositions from Swift names (declination part)degpos.eq.dec;meta.mainJ/ApJS/209/9/table4UGSs without XRT-PC counterparts in the Fermi LAT positional uncertainty regionrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2FGL2FGL name (JHHMM.m+DDMM)meta.id;meta.maincharf_2FGL[*] *: Flag on 2FGL (1)meta.codecharExp[142/10728] XRT-PC total exposure timestime.duration;obs.exposureintJ/ApJS/209/9/table5XRT-PC counterparts to {gamma}-ray blazar-like sources selected according to Papers I and V.recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2FGL2FGL name (JHHMM.m+DDMM)meta.id;meta.maincharSwiftSwift designation (JHHMMSS.s+DDMMSS)meta.id.crosscharf_Swift[*] *: source with radio counterpart within the positional error listed in table 1meta.codecharANameWISE designation (JHHMMSS.ss+DDMMSS.s) or WN0557.5+3838 (in table 5) (1)meta.idcharCl[A-C ] Classification (A=most probable candidate blazar; only for table 5) (2)meta.code.qualcharOTypeObject type (only for table 5) (3)src.classcharJ/ApJS/209/9/table6XRT-PC counterparts to {gamma}-ray blazar-like sources selected with the KDE techniquerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2FGL2FGL name (JHHMM.m+DDMM)meta.id;meta.maincharSwiftSwift designation (JHHMMSS.s+DDMMSS)meta.id.crosscharf_Swift[*] *: source with radio counterpart within the positional error listed in table 1meta.codecharANameWISE designation (JHHMMSS.ss+DDMMSS.s) or WN0557.5+3838 (in table 5) (1)meta.idcharCl[A-C ] Classification (A=most probable candidate blazar; only for table 5) (2)meta.code.qualcharOTypeObject type (only for table 5) (3)src.classchar