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Astron. Astrophys. 323, 620-633 (1997)

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The Hipparcos Catalogue as a realisation of the extragalactic reference system

J. Kovalevsky 1, L. Lindegren 2, M.A.C. Perryman 3, P.D. Hemenway 4, K.J. Johnston 5, V.S. Kislyuk 6, J.F. Lestrade 7, L.V. Morrison 8, I. Platais 9, S. Röser 10, E. Schilbach 11, H.-J. Tucholke 12, C. de Vegt 13, J. Vondrák 14, F. Arias 15, A.M. Gontier 16, F. Arenou 7, P. Brosche 12, D.R. Florkowski 5, S.T. Garrington 17, R.A. Preston 18, C. Ron 14, S.P. Rybka 6, R.-D. Scholz 11 and N. Zacharias 5

1 CERGA, Observatoire de la Côte d'Azur, Av. Copernic, F-06130 Grasse, France
2 Lund Observatory, Box 43, S-22100 Lund, Sweden
3 Astrophysics Division, European Space Agency, ESTEC, Noordwijk 2200 AG, The Netherlands
4 Astronomy Dept., University of Texas, RLM 15308, Austin, TX 78712 1083, USA
5 US Naval Observatory, 3450 Massachusetts Ave NW, Washington DC, 20392, USA
6 Main Astron. Observatory Ukrainian Ac. Sc., Goloseevo, 252127 Kiev, Ukraine
7 Observatoire de Paris, Section de Meudon, F-92195 Meudon Principal Cedex, France
8 Royal Greenwich Observatory, Madingley Road, Cambridge CB3 0EZ, UK
9 Yale University Observatory, PO Box 208101, New Haven CT 06520-8101, USA
10 Astronomisches Rechen-Institut, Mönchhofstrasse 12-14, D-69120 Heidelberg, Germany
11 WIP, Universität Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany
12 Universitäts Sternwarte, Auf dem Hügel 71, D-53121 Bonn, Germany
13 Hamburger Sternwarte, Gojensbergsweg 112, D-21029 Hamburg, Germany
14 Astronomical Institute, Boní II 1401, 14131 Prague 4, Czechien
15 Observatorio Astronomico, Paseo del Bosque, S/N, 1900 La Plata, Argentina
16 IERS, Observatoire de Paris, 61, avenue de l'Observatoire, F-75014 Paris, France
17 University of Manchester, NRAL, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK
18 Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA

Received 15 October 1996 / Accepted 8 November 1996


The paper describes the methods and observations by which the Hipparcos Catalogue was linked to the International Celestial Reference System (ICRS). The contributions of several groups represented in the authorship of this paper, using a variety of techniques, were synthesised in order to determine the global orientation and rotation (spin) of the coordinate frame defined by the Hipparcos data with respect to extragalactic sources. The following link techniques were used: interferometric observations of radio stars by VLBI networks, MERLIN and VLA; observations of quasars relative to Hipparcos stars by means of CCDs and photographic plates, and by the Hubble Space Telescope; photographic programmes to determine stellar proper motions with respect to extragalactic objects (Bonn, Kiev, Lick, Potsdam, Yale/San Juan); and comparison of Earth orientation parameters obtained by VLBI and by ground-based optical observations of Hipparcos stars. Although vastly different in terms of instruments, observational methods and objects involved, the various techniques generally agree to within 10 mas (milliarcsec) in the orientation and 1 mas/yr in the spin of the system. Two different numerical methods are described for the systematic comparison and synthesis of the link observations. The methods give very similar solutions, and a mean value was adopted for the definition of the system of positions and proper motions in the Hipparcos Catalogue. As a result, the coordinate axes defined by the published catalogue are believed to be aligned with the extragalactic radio frame to within [FORMULA]  mas at the epoch 1991.25, and non-rotating with respect to distant extragalactic objects to within [FORMULA]  mas/yr.

Key words: astrometry – catalogs – reference systems

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998