J/A+A/325/167ivo://CDS.VizieR/J/A+A/325/167doi:10.26093/cds/vizier.33250167CDSRaboud D.Cramer N.Bernasconi P.A.2018-01-05T08:56:02Z2007-07-29T08:47:01ZCDS support team

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

cds-question@unistra.fropen-star-clustersvisible-astronomynarrow-band-photometryWe present photoelectric (127 stars) and CCD (168 stars) Geneva photometry for the very young open cluster NGC 6231. We have searched for new cluster members out to a distance of ~13arcmin, extending the Seggewiss area (~8arcmin), and we found at least 64 new probable members in this extended field. Differential reddening is clearly measured across the cluster area. We determine the cluster distance (1800pc) and age (3.8+/-0.6x10^6^yr). The probable presence of pre-main sequence stars and the consequence of this population on the cluster formation history is analysed. We also found that the O8.5III star S161 is a long term variable and we present its light curve extending over more than 20 years. Finally we discuss the existence of Ap stars in the cluster. For a description of the Geneva photometric system, see e.g. <GCPD/13>1997A&A...325..167Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/325/167CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/315/384 : Binarity among B-stars in NGC 6231 (Raboud, 1996)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/325/167https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/325/167http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/325/167https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/325/167https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/325/167http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/325/167GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/325/167/data (Geneva photometry in NGC 6231)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/325/167/data?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/325/167/data?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/325/167/data?GETtext/xml+votable180.050000true253.5145833-41.71441670.0055555555555555566/42383 42394-42396 42405 42416-42417https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/325/167?format=asciiOpticaldefaultJ/A+A/325/167/dataGeneva photometry in NGC 6231NumberStar numbermeta.id;meta.maincharEbvColour excessmagphot.color.excessfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintf_NumberSimbad column added by the CDSmeta.codecharn_Number[1]? '1' indicates a CCD measurementmeta.noteintnullableClass[nm? ] Membership (m=member, nm=non-member)meta.code.membercharn_Class? Remark on classification. See Note (3)meta.noteintnullableVmagApparent V magnitudemagphot.mag;em.opt.VfloatXX parameter in Geneva photometrymagphot.color.reddFreefloatYY parameter in Geneva photometrymagphot.color.reddFreefloatZZ parameter in Geneva photometrymagphot.color.reddFreefloatVMAG? Absolute V magnitudemagphys.magAbs;em.opt.VfloatnullableU-BU-B Geneva colourmagphot.color;em.opt.U;em.opt.BfloatB-VB-V Geneva colourmagphot.color;em.opt.B;em.opt.VfloatXposX coordinate centered on S289 (2)pixpos.cartesian.x;instr.detfloatYposY coordinate centered on S289 (2)pixpos.cartesian.y;instr.detfloatSpTEstimated photometric spectral type (for table3 and 5) or Rejection criteria (for table4)src.spTypecharSimbadNameSimbad column added by the CDSmeta.idchar_RAComputed Right Ascension for Equinox: J2000degpos.eq.ra;meta.main_DEComputed Declination for Equinox: J2000degpos.eq.dec;meta.main