J/A+A/425/1107ivo://CDS.VizieR/J/A+A/425/1107doi:10.26093/cds/vizier.34251107CDSVieira Martins R.Veiga C. H.Bourget P.Andrei A. H.Descamps P.2004-12-11T20:39:31Z2004-12-11T21:38:47ZCDS support team

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

cds-question@unistra.frsolar-system-planetsastrometryEarth based observations of Proteus are made highly difficult by the magnitude difference with Neptune, and the closeness to the planet. To overcome these difficulties, observation campaigns using a Hg-mask coronograph developed for astrometry are being pursued at the Laboratorio Nacional de Astrofisica, Brazil. The observations are made at visible light wavelengths with the 1.6 m reflector telescope. The large 4'x4' field of view of the camera makes it possible to image a sufficient number of background stars that are used to carry out the astrometric analysis of these data. The first results of the campaigns are presented in this paper. They include 45 independent observations made over 2 nights in 2002. The positions are referred to the Hipparcos/Tycho2 (<I/239>/<I/259>)frame. The mean offsets relative to the JPL ephemeris are =0.083" ({sigma}=0.148") in the x={DELTA}RAcosDE direction, and -0.051" ({sigma}=0.115") in the y={DELTA}DE direction. Additional astrometric data need to be collected in order to investigate further the possible offset of Proteus with respect to the Voyager ephemerides.2004A&A...425.1107Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/425/1107CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/120/107 : 1989-1994 CCD observations of Triton (Veiga+ 1996)J/A+AS/131/291 : 1995-1997 CCD positions of Triton (Veiga+ 1998)J/AJ/119/936 : 2000-2009 Triton stel. occultation candidates (McDonald+ 2000)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/425/1107https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/425/1107http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/425/1107https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/425/1107https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/425/1107http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/425/1107GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/425/1107/catalog (Topocentric observed positions of Triton and Proteus)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/425/1107/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/425/1107/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/425/1107/catalog?GETtext/xml+votable180.050000true306.05405833-19.122694440.0055555555555555566/48734 48745 48754https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/425/1107?format=asciidefaultJ/A+A/425/1107/catalogTopocentric observed positions of Triton and ProteusrecnoRecord number assigned by the VizieR team. Should Not be used for identification.intJDJulian Date and fractions of ObservationddoubleRAtTriton Right Ascention (J2000)DEtTriton Declination (J2000)RApProteus Right Ascention (J2000)DEpProteus Declination (J2000)