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Astron. Astrophys. 323, 620-633 (1997) 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
Received 15 October 1996 / Accepted 8 November 1996 Abstract 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
Key words: astrometry Contents
© European Southern Observatory (ESO) 1997 Online publication: June 5, 1998 ![]() |