J/ApJ/756/33ivo://CDS.VizieR/J/ApJ/756/33doi:10.26093/cds/vizier.17560033CDSCheung C.C.Donato D.Gehrels N.Sokolovsky K.V.Giroletti M.2021-08-04T12:20:50Z2021-08-04T13:19:17ZCDS support team

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

cds-question@unistra.frx-ray-sourcesgamma-ray-astronomyWe present Chandra ACIS-I X-ray observations of 0FGL J1311.9-3419 and 0FGL J1653.4-0200, the two brightest high Galactic latitude (|b|>10{deg}) {gamma}-ray sources from the three-month Fermi Large Area Telescope (LAT) bright source list that are still unidentified. Both were also detected previously by EGRET, and despite dedicated multi-wavelength follow-up, they are still not associated with established classes of {gamma}-ray emitters like pulsars or radio-loud active galactic nuclei. X-ray sources found in the ACIS-I fields of view are cataloged, and their basic properties are determined. These are discussed as candidate counterparts to 0FGL J1311.9-3419 and 0FGL J1653.4-0200, with particular emphasis on the brightest of the 9 and 13 Chandra sources detected within the respective Fermi-LAT 95% confidence regions. Further follow-up studies, including optical photometric and spectroscopic observations, are necessary to identify these X-ray candidate counterparts in order to ultimately reveal the nature of these enigmatic {gamma}-ray objects.2012ApJ...756...33Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/756/33CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2014)J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)J/MNRAS/424/L64 : AGN/pulsar distinction for 2FGL sources (Mirabal+, 2012)J/ApJ/753/83 : Associations to 1FGL sources (Ackermann+, 2012)J/ApJ/742/66 : New Fermi/LAT extragalactic sources (Teng+, 2011)J/ApJ/741/30 : Radio/{gamma}-ray correlation in AGN (Ackermann+, 2011)J/ApJS/188/405 : Fermi-LAT first source catalog (1FGL) (Abdo+, 2010)J/ApJ/706/L7 : The Fermi LAT sky as seen by INTEGRAL/IBIS (Ubertini+, 2009)J/ApJ/700/597 : FERMI LAT detected blazars (Abdo+, 2009)J/ApJS/183/46 : Fermi/LAT bright gamma-ray source list (0FGL) (Abdo+, 2009)J/A+A/489/849 : Revised cat. of EGRET gamma-ray sources (Casandjian+, 2008)J/A+A/458/245 : 2 Unidentified Gamma-ray Sources obs. (La Palombara+, 2006)http://cxc.harvard.edu/cal/ASPECT/celmon/ : Chandra astrometric accuracy pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/756/33https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/756/33http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/756/33https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/756/33https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/756/33http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/756/33GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/756/33/Xsources (All X-ray sources found in the field of the four ACIS-I chips in the Chandra observation of 0FGL J1311.9-3419 (table 5) or 0FGL J1653.4-0200 (table 6))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/756/33/Xsources?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/756/33/Xsources?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/756/33/Xsources?GETtext/xml+votable180.050000true197.7744-34.447850.0055555555555555566/31110 31116 43819 43905https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/756/33?format=asciiGamma-rayX-raydefaultJ/ApJ/756/33/XsourcesAll X-ray sources found in the field of the four ACIS-I chips in the Chandra observation of 0FGL J1311.9-3419 (table 5) or 0FGL J1653.4-0200 (table 6)NSig[0.5/40] Ncts significancestat.fit.goodnessfloatSeq[1/97] Running sequence numbermeta.idint0FGL0FGL fieldobs.fieldcharCXOUChandra name (HHMMSS.s+DDMMSS; J2000)meta.id;meta.maincharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainePos[0.03/1.9] Source localization error (r)arcsecstat.errorfloatSep[0.7/10.2] Distance from the Chandra aim pointarcminpos.angDistancefloatAeff[166/507] Effective area at the source position at 1.5keV (1)cm**2phys.area;instrintlogPks[-2/0]? Logarithm probability from the KS test for variability (logP_K-S_)stat.fit.goodness;src.varfloatnullableNcts[1.4/1674] Net counts in the 0.5-8keV bandctphot.count;em.X-rayfloatE_Ncts[2.7/42] Positive error on Nctsctstat.error;stat.maxfloate_Ncts[1.3/41] Negative error on Nctsctstat.errorfloatNPb[0/1] Probability (Pb) that the source counts are solely from the background in the 0.5-8keVstat.fit.goodnessdoubleScts[-0.9/1139] Net counts in the 0.5-2keV bandctphot.count;em.X-rayfloatE_Scts[1.9/35] Positive error on Sctsctstat.error;stat.maxfloate_Scts[0/34] Negative error on Sctsctstat.errorfloatSSig[-0.5/33] Scts significancestat.fit.goodnessfloatSPb[0/1] Probability (Pb) that the source counts are solely from the background in the 0.5-2keVstat.fit.goodnessdoubleHcts[-1.7/536] Counts in the 2-8keV bandctphot.count;em.X-rayfloatE_Hcts[1.9/25] Positive error on Hctsctstat.error;stat.maxfloate_Hcts[0/24] Negative error on Hctsctstat.errorfloatHSig[-0.9/22.1] Hcts significancestat.fit.goodnessfloatHPb[0/1] Probability (Pb) that the source counts are solely from the background in the 2-8keVstat.fit.goodnessdoubleUSNO-BPotential counterpart match(es) from the USNO B1.0 catalog (I/284) (from table 7)meta.id.crosscharnullable2MASSPotential counterpart match from the 2MASS catalog (II/246) (from table 8)meta.id.crosscharWISEPPotential counterpart match from the WISEP catalog (II/307) (from table 9)meta.id.crosschar