J/AJ/140/1500ivo://CDS.VizieR/J/AJ/140/1500doi:10.26093/cds/vizier.51401500CDSMontiel E.J.Mighell K.J.2012-08-27T23:24:43Z2012-08-06T20:32:27ZCDS support team

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

cds-question@unistra.frglobular-star-clustersvariable-starshst-photometryWe have analyzed archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations of the central region of the globular cluster M54. The 12 irregularly timed observations (6 F555W, 6 F814W) were reduced using the HSTphot stellar photometry package. Our statistical analysis of the HSTphot photometry yielded 50 variable stars that are likely RR Lyrae candidates. These candidates were missed by previous ground-based searches for RR Lyraes due to the extreme crowding in the core of M54. We performed two checks on our sample of RR Lyrae candidates to determine how different they were from the other variable candidates.2010AJ....140.1500Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/140/1500CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/109/1086 : VI Photometry in M54 and Sgr Dwarf Galaxy (Sarajedini+ 1995)J/AJ/118/1245 : Elemental abundances in five stars in M54 (Brown+, 1999)J/AJ/119/1760 : M54 and Sgr dSph VI photometry (Layden+, 2000)J/A+A/520/A95 : Abundances of red giants in M54 & Sgr dSph (Carretta+, 2010)J/MNRAS/406/329 : Variable stars in M54 (Sollima+, 2010)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/140/1500https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/140/1500http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/140/1500https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/140/1500https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/140/1500http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/140/1500GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/140/1500/table2 (RR Lyrae candidates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/140/1500/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/140/1500/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/140/1500/table2?GETtext/xml+votable180.050000true283.767375-30.47730560.0055555555555555566/48035https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/140/1500?format=asciiOpticaldefaultJ/AJ/140/1500/table3PhotometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharOIDObservation identification; see Table 1meta.id;obs.param;obscharmagObserved magnitude in bandmagphot.magfloate_magThe 1{sigma} error in magmagstat.error;phot.magfloatBand[IV] Observed band (I for F814W, V for F555W)instr.bandpasscharMJDModified Julian Date of observationdtime.epochdoubleJ/AJ/140/1500/table1Observation LogrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSetData Setmeta.idcharFiltFilter namemeta.id;instr.filtercharTexpExposure timestime.duration;obs.exposurefloatMJDModified Julain Datedtime.epochdoubleDt1Difference in time between the first observation and subsequent observationstime;arith.diffnullableOIDObservation IDmeta.id;obscharJ/AJ/140/1500/table2RR Lyrae candidatesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar name, VCNNmeta.id;meta.maincharprimaryIDIdentification number (1)meta.idlongRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.main<Vmag>Mean V magnitudemagphot.mag;em.opt.Vfloate_<Vmag>rms uncertainty on <Vmag>magstat.error;phot.mag;em.opt.Vfloat<Imag>Mean I magnitudemagphot.mag;em.opt.Ifloate_<Imag>rms uncertainty on <Imag>magstat.error;phot.mag;em.opt.Ifloatchi2chi^2^ VIstat.fit.chi2floatLClight curvesmeta.ref.urlchar