J/PASP/106/404ivo://CDS.VizieR/J/PASP/106/404doi:10.26093/cds/vizier.61060404CDSSARAJEDINI A.2025-09-09T14:11:47Z1997-12-09T21:44:53ZCDS support team

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

cds-question@unistra.frglobular-star-clustersccd-photometryThe first CCD color-magnitude diagram (CMD) in B and V is presented for the Galactic globular cluster NGC 6535. From this CMD, which extends below the main-sequence turnoff, we draw the following conclusions: (1) The horizontal branch (HB) is predominantly blue in nature with no RR Lyrae variables known to be cluster members. Nonetheless, based on a comparison with clusters which have blue HBs and RR Lyraes (M15 and M79), we infer a mean HB magnitude of <V(RR)>=15.73+/-0.11 for NGC 6535. (2) Again, via a direct comparison with the blue HBs of M15 and M79, we derive a cluster reddening of E(B-V)=0.44+/-0.02. (3) When combined with the apparent color of the red-giant branch at the level of the HB, (B-V)g=1.18+/-0.02, the derived reddening yields a metal abundance of [Fe/H]=-1.85+/-0.10, similar to that of NGC 6397. (4) Application of the Delta(V(TO-HB)) and Delta((B-V)(SGB-TO)) cluster dating techniques reveals no perceptible age difference between NGC 6535 and NGC 6397. (5) A significant population of nine blue-straggler candidates is detected in NGC 6535. However, this is too few to facilitate a meaningful analysis of their radial distribution. Addresses: Sarajedini A. ata@noao.edu Kitt Peak National Observatory, National Optical Astronomy Observatories, P.O. Box 26732, Tucson, Arizona 85726-67321994PASP..106..404Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/PASP/106/404CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/PASP/106/404https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/PASP/106/404http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/PASP/106/404https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/PASP/106/404https://vizier.iucaa.in/viz-bin/votable?-source=J/PASP/106/404http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/PASP/106/404GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/PASP/106/404/table2Photometry of NGC 6535recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDStar numbermeta.id;meta.mainintXX CCD coordinatepixpos.cartesian.x;instr.detfloatYY CCD coordinatepixpos.cartesian.y;instr.detfloatVmagVisual magnitudemagphot.mag;em.opt.VfloatB-VB-V colormagphot.color;em.opt.B;em.opt.Vfloato_VmagNumber of observationsmeta.numberint