J/AJ/103/638ivo://CDS.VizieR/J/AJ/103/638doi:10.26093/cds/vizier.51030638CDSMonet D.G.Dahn C.C.Vrba F.J.Harris H.C.Pier J.R.Luginbuhl C.B.,Ables H.D.2023-04-06T16:49:25Z2009-03-13T12:13:31ZCDS support team

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

cds-question@unistra.frvisible-astronomytrigonometric-parallaxphotometryproper-motionsThe U.S. Naval Observatory CCD trigonometric parallax program is described in detail, including the instrumentation employed, observing procedures followed, and reduction procedures applied. Astrometric results are presented for 72 stars ranging in apparent brightness from V=15.16 to 19.58. Photometry (V and V-I on the Kron-Cousins system) is presented for the parallax stars and for all 426 individual reference stars employed in the astrometric solutions. Corrections for differential color refraction, calibrated to the observed V-I colors, have been applied to all astrometric measures. The mean errors in the relative parallaxes range from +/-0.0005" to +/-0.0027" with a median value of +/-0.0010". Seventeen of the 23 stars with V_tan_>200km/s form a well-delineated sequence of extreme subdwarfs covering 11.5<M_V_<14.5 in the M_V_ vs V-I diagram. The transformation to the M_bol_ vs log T_eff_ plane is presented and the results are compared with various model interior computations. Within the limitations due to the uncertain T_eff_ scale for cool dwarfs and subdwarfs, the coolest members of the extreme subdwarf sequence appear to be near the hydrogen-burning minimum mass limit for stars with metallicities of [M/H]~-2.1992AJ....103..638Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/103/638CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/87 : LHS Catalogue, 2nd Edition (Luyten 1979)J/AJ/105/1571 : USNO Photographic Parallaxes. IX (Harrington+ 1993)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/103/638https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/103/638http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/103/638https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/103/638https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/103/638http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/103/638GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/103/638/table1 (Astrometric and photometric results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/103/638/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/103/638/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/103/638/table1?GETtext/xml+votable180.050000true7.838419.606010.0055555555555555566/5 578 1084 1332 1407 1840 2330 2655 3661 3933 4142 4450 4685 6150 6207 6328 8405 8531 8783 9146 9477 9723 10103 10348 11159 11172 11496 12576 13470 13641 13695 13765 14910 15071 15239 15543 16125 17452 17967 19545 19786 19932 20099 21835 22345 22366 23144 23310 24171 24213 25310 26445 27413 27704 28354 29777 29798 29968 30045 30505 30833 30955 31022 40361 40941 48778 489263.352923723967259e-19 3.9105737390043815e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/103/638?format=asciiOpticaldefaultJ/AJ/103/638/table1Astrometric and photometric resultsSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUSNOSequential numbermeta.idintNote[n] note detailed in notes.dat filemeta.notecharLHS? LHS (Luyten, 1979, Cat. <I/87>) numbermeta.idcharn_Name[*] *: observations are continuing (Sect. 6)meta.notecharNameNamemeta.idcharRA1950Right ascension (1950)pos.eq.ra;meta.mainDE1950Declination (1950)pos.eq.dec;meta.mainNfNumber of CCD frames employed in the solutionmeta.numberintNnNumber of separate nights on which the frame were takenmeta.numberintNsNumber of reference stars employed in the solutionmeta.id;meta.mainintplxrRelative trigonometric parallaxmaspos.parallax.trigfloate_plxrrms uncertainty on plxrmasstat.errorfloatpmTotal relative proper motionmas/yrpos.pmfloate_pmrms uncertainty on mumas/yrstat.errorfloatpmPARelative position angle of the total proper motion (measured north to east)degpos.pm;pos.posAngfloate_pmPArms uncertainty on pmPAdegstat.errorfloatVmagV magnitude in the Kron-Cousins systemmagphot.mag;em.opt.VfloatV-IV-I colour index in the Kron-Cousins systemmagphot.color;em.opt.V;em.opt.IfloatplxAbsolute trigonometric parallaxmaspos.parallax.trigfloate_plxrms uncertainty on plxmasstat.error;pos.parallaxfloatVMAGAbsolute V magnitudemagphys.magAbs;em.opt.Vfloate_VMAGrms uncertainty on VMAGmagstat.errorfloatVtanTangential velocitykm/sphys.velocfloate_Vtanrms uncertainty on Vtankm/sstat.errorfloatDT1Date of the first frame employed (1900+)yrtime.epochfloatDT2Date of the last frame employed (1900+)yrtime.epochfloat_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into account (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into account (computed by VizieR, not part of the original data)pos.eq.decnullableindexedJ/AJ/103/638/notesIndividual notesUSNOUSNO numbermeta.idintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTextText of the notemeta.notechar