J/AJ/109/639ivo://CDS.VizieR/J/AJ/109/639doi:10.26093/cds/vizier.51090639CDSSosin C.King I.R.2023-04-06T16:50:12Z1997-12-09T20:26:18ZCDS support team

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

cds-question@unistra.frglobular-star-clustersphotometryastrometryWe have used the Faint Object Camera on the Hubble Space Telescope (HST) to observe three fields near the center of the post-collapse globular cluster NGC 6624 in B and V. We use individual stellar positions and a maximum-likelihood technique to measure a position for the cluster center. We then transfer this position and the position of the x-ray source 4U 1820-30 to right ascension and declination, and correct an error of 1.8" in an earlier paper. From star counts, we obtain a density profile, with a power-law cusp of slope -0.84 +/- 0.16. No flat core is evident. We construct color-magnitude diagrams down to the main-sequence turnoff near the cluster center, and more than three magnitudes below the turnoff in the outermost field at r=28". The former diagram reveals a central population of blue stragglers, which has not previously been observed in this cluster. These blue stragglers are quite similar in specific frequency to those recently observed by HST in the core of 47 Tuc, and their presence adds to the growing evidence of stellar interactions in dense globular-cluster cores.1995AJ....109..639Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/109/639CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/109/639https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/109/639http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/109/639https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/109/639https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/109/639http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/109/639GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/109/639/table1Photometry of all stars brighter than V = 20 in our inner two fields in NGC 6624recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentification numbermeta.id;meta.mainintField*[1,2] Field numberobs.fieldintXposX coordinate on F480LP image under Fieldpixpos.cartesian.x;instr.detfloatYposY coordinate on F480LP image under Fieldpixpos.cartesian.y;instr.detfloatoRA*RA (J2000) relative to cluster centerarcsecpos.eq.ra;arith.difffloatoDE*Dec (J2000) relative to cluster centerarcsecpos.eq.dec;arith.difffloatm480F480LP instrumental magnitudemagphot.mag;em.opt.Bfloatm430-m480F430W - F480LP color (HST instr. system)magphot.color;em.opt.B;em.opt.VfloatVmagV magnitudemagphot.mag;em.opt.VfloatB-VB-V colormagphot.color;em.opt.B;em.opt.VfloatCommentCommentsmeta.notecharJ/AJ/109/639/table2Photometry of all stars brighter than V = 23 in our outermost FOC field in NGC 6624recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentification numbermeta.id;meta.mainintXposX coord. on outermost (r=28") F480LP imagepixpos.cartesian.x;instr.detfloatYposY coord. on outermost (r=28") F480LP imagepixpos.cartesian.y;instr.detfloatoRA*RA (J2000) relative to star at (257,286)arcsecpos.eq.ra;arith.difffloatoDE*Dec (J2000) relative to star at (257,286)arcsecpos.eq.dec;arith.difffloatm480F480LP instrumental magnitudemagphot.mag;em.opt.Bfloatm430-m480F430W - F480LP color (HST instr. system)magphot.color;em.opt.B;em.opt.VfloatVmagV magnitudemagphot.mag;em.opt.VfloatB-VB-V colormagphot.color;em.opt.B;em.opt.Vfloat