J/A+A/478/755ivo://CDS.VizieR/J/A+A/478/755doi:10.26093/cds/vizier.34780755CDSde Jong J.T.A.Kuijken K.H.Heraudeau P.2008-03-26T20:42:34Z2008-03-26T21:41:14ZCDS support team

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

cds-question@unistra.frgalaxiesvariable-starsDifference imaging has proven to be a powerful technique for detecting and monitoring the variability of unresolved stellar sources in M 31. Using this technique in surveys of galaxies outside the Local Group could have many interesting applications. The goal of this paper is to test difference imaging photometry on Centaurus A, the nearest giant elliptical galaxy, at a distance of 4Mpc. We obtained deep photometric data with the Wide Field Imager at the ESO/MPG 2.2m at La Silla spread over almost two months. Applying the difference imaging photometry package DIFIMPHOT, we produced high-quality difference images and detected variable sources. The sensitivity of the current observational setup was determined through artificial residual tests. In the resulting high-quality difference images, we detect 271 variable stars. We find a difference flux detection limit corresponding to m_R_~=24.5. Based on a simple model of the halo of Centaurus A, we estimate that a ground-based microlensing survey would detect in the order of 4 microlensing events per year due to lenses in the halo. Conclusions: Difference imaging photometry works very well at the distance of Centaurus A and promises to be a useful tool for detecting and studying variable stars in galaxies outside the local group. For microlensing surveys, a higher sensitivity is needed than achieved here, which would be possible with a large ground-based telescope or space observatory with wide-field imaging capabilities.2008A&A...478..755Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/478/755CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/478/755https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/478/755http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/478/755https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/478/755https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/478/755http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/478/755GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/478/755/table3 (Variable stars in Centaurus A)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/478/755/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/478/755/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/478/755/table3?GETtext/xml+votable180.050000true201.6501-42.7940.0055555555555555566/43262-43263 43604https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/478/755?format=asciiOpticaldefaultJ/A+A/478/755/table3Variable stars in Centaurus ArecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCAVSCAVS numbermeta.id;meta.mainintRAJ2000Right ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainPer? Perioddtime.periodfloatnullableVTypeType of variation: V* = variable star, No* = Nova variablemeta.code;src.varchar