J/PASP/122/288ivo://CDS.VizieR/J/PASP/122/288doi:10.26093/cds/vizier.61220288CDSPiatti A.E.Claria J.J.Ahumada A.V.2025-09-09T14:13:51Z2010-09-09T12:37:24ZCDS support team

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

cds-question@unistra.fropen-star-clustersccd-photometryinfrared-photometryvisible-astronomybroad-band-photometryWe have obtained CCD UBVI_KC_ photometry down to V~22.0 for the open cluster NGC 2309 and its surrounding field. Twenty three probable cluster members have been identified for the first time on the basis of sound photometric criteria. Because NGC 2309 is a relatively poor cluster projected onto a rich star field showing density fluctuations, the frequently used membership criteria based on stellar density profiles or proper motion measurements would not be enough to assess the star membership status if employed independently. We estimated a cluster radius of 7.9' and a radius at half the maximum of the cluster density profile of 1.7'. Based on the best fits of isochrones computed by the Geneva group to the cluster color-magnitude and color-color diagrams, previously shifted by the cluster reddening (E(B-V)=0.32) and distance (d=2.5kpc), we derived the cluster age (250Myr) and metallicity ([Fe/H]~0.0). If an 8.5kpc distance from the Sun to the center of the Galaxy is assumed, then NGC 2309 is found to be located just in front of the Perseus spiral arm.2010PASP..122..288Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/PASP/122/288CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/PASP/122/288https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/PASP/122/288http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/PASP/122/288https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/PASP/122/288https://vizier.iucaa.in/viz-bin/votable?-source=J/PASP/122/288http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/PASP/122/288GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/PASP/122/288/table2 (UBVI data of stars in the field of NGC 2309)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/PASP/122/288/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/PASP/122/288/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/PASP/122/288/table2?GETtext/xml+votable180.050000true104.0529661-7.04279080.0055555555555555566/21679 21690 22021 22032https://cdsarc.cds.unistra.fr/viz-bin/moc/J/PASP/122/288?format=asciiOpticalInfrareddefaultJ/PASP/122/288/table2UBVI data of stars in the field of NGC 2309recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/2275] Sequential numbermeta.recordintXposX position (1)pixpos.cartesian.x;instr.detdoubleYposY position (1)pixpos.cartesian.y;instr.detdoubleVmagJohnson V magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.Vfloato_VmagNumber of observation for Vmagmeta.numberintU-B? Johnson U-B colour indexmagphot.color;em.opt.U;em.opt.Bfloatnullablee_U-B? rms uncertainty on U-B (2)magstat.error;phot.color;em.opt.Ufloatnullablen_U-BNumber of observation for U-Bmeta.noteintB-V? Johnson B-V colour indexmagphot.color;em.opt.B;em.opt.Vfloatnullablee_B-V? rms uncertainty on B-V (2)magstat.error;phot.color;em.opt.Bfloatnullablen_B-VNumber of observation for B-Vmeta.noteintV-Ic? Johnson-Cousins V-I colour indexmagphot.color;em.opt.V;em.opt.Ifloatnullablee_V-Ic? rms uncertainty on V-Ic (2)magstat.error;phot.color;em.opt.Vfloatnullable_RAPosition computed from a comparison with UCAC3 (Cat. I/315,{sigma}=0.15'') (right ascension part)degpos.eq.ra;meta.main_DEPosition computed from a comparison with UCAC3 (Cat. I/315,{sigma}=0.15'') (declination part)degpos.eq.dec;meta.main