J/ApJ/725/331ivo://CDS.VizieR/J/ApJ/725/331doi:10.26093/cds/vizier.17250331CDSYelda S.Lu J.R.Ghez A.M.Clarkson W.Anderson J.Do T.Matthews K.2012-09-10T07:42:07Z2012-08-23T07:21:46ZCDS support team

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

cds-question@unistra.frgalaxy-planesmilky-way-galaxyastrometryastronomical-modelsproper-motionsinfrared-photometryWe present significantly improved proper motion measurements of the Milky Way's central stellar cluster. These improvements are made possible by refining our astrometric reference frame with a new geometric optical distortion model for the W. M. Keck II 10m telescope's adaptive optics camera (NIRC2) in its narrow field mode. For the first time, this distortion model is constructed from on-sky measurements and is made available to the public in the form of FITS files. When applied to widely dithered images, it produces residuals in the separations of stars that are a factor of ~3 smaller compared with the outcome using previous models. By applying this new model, along with corrections for differential atmospheric refraction, to widely dithered images of SiO masers at the Galactic center (GC), we improve our ability to tie into the precisely measured radio Sgr A*-rest frame. The resulting infrared reference frame is ~2-3 times more accurate and stable than earlier published efforts. In this reference frame, Sgr A* is localized to within a position of 0.6mas and a velocity of 0.09mas/yr, or ~3.4km/s at 8kpc (1{sigma}). Also, proper motions for members of the central stellar cluster are more accurate, although less precise, due to the limited number of these wide field measurements. We define a reference frame with SiO masers and this reference frame's stability should improve steadily with future measurements of the SiO masers in this region ({propto}t^-3/2^). This is essential for achieving the necessary reference frame stability required to detect the effects of general relativity and extended mass on short-period stars at the GC.2010ApJ...725..331Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/725/331CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/270 : TCS-CAIN: NIR Survey of the Galactic plane (Cabrera-Lavers+, 2006)J/MNRAS/417/114 : HST/NICMOS Galactic Center survey catalogue (Dong+, 2011)J/A+A/534/A117 : NIR polarimetry of sources near SgrA* (Buchholz+, 2011)J/A+A/511/A18 : NIR observations of stars near SgrA* (Schoedel+, 2010)J/ApJ/707/L114 : The orbit of S2 star around Sgr A* (Gillessen+, 2009)J/A+A/502/91 : Proper motions of stars near SgrA* (Schoedel+, 2009)J/A+A/499/483 : NIR observations of sources in galactic center (Buchholz+,J/ApJ/670/1115 : IRS spectra at 38 positions in Galactic center (Simpson+,J/ApJ/659/1241 : Stellar variability in Galactic Center (Rafelski+, 2007)J/ApJ/643/1011 : Early-type stars in the center of the Galaxy (Paumard+, 2006)J/ApJ/642/861 : N-band imaging of the Galactic Center (Viehmann+, 2006)J/ApJ/470/864 : JHKL photometry of the Galactic Center (Blum+, 1996)http://www.astro.ucla.edu/~ghezgroup/distortion/ : Ghez Research Grouphttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/725/331https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/725/331http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/725/331https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/725/331https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/725/331http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/725/331GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/725/331/table7 (Galactic center secondary IR astrometric standards (with corrections from erratum: ApJ, 726, 114))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/725/331/table7?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/725/331/table7?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/725/331/table7?GETtext/xml+votable180.050000true266.416943519-29.0077775280.0055555555555555566/28830https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/725/331?format=asciiInfrareddefaultJ/ApJ/725/331/table7Galactic center secondary IR astrometric standards (with corrections from erratum: ApJ, 726, 114)NameSource namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKpmagK' band magnitudemagphot.mag;em.IR.KfloatEpIRAverage time of the IR positional measurementsyrtime.epochfloatRadRadius from Sgr A*arcsecpos.angDistancefloatoRAOffset in Right Ascension from Sgr A*arcsecpos.eq.ra;arith.difffloate_oRAUncertainty in oRA (1)masstat.errorfloatoDEOffset in Declination from Sgr A*arcsecpos.eq.dec;arith.difffloate_oDEUncertainty in oDE (1)masstat.errorfloatpmRARight Ascension proper motionmas/yrpos.pm;pos.eq.rafloate_pmRAUncertainty in pmRA (2)mas/yrstat.error;pos.pm;pos.eq.rafloatpmDEDeclination proper motionmas/yrpos.pm;pos.eq.decfloate_pmDEUncertainty in pmDE (2)mas/yrstat.error;pos.pm;pos.eq.decfloat_RACoordinates, computed from oRA, oDE with SgrA* position at 17:45:40.0409-29:00:28.118 (from Simbad) (right ascension part)degpos.eq.ra;meta.main_DECoordinates, computed from oRA, oDE with SgrA* position at 17:45:40.0409-29:00:28.118 (from Simbad) (declination part)degpos.eq.dec;meta.main