Issue |
Astron. Astrophys. Suppl. Ser.
Volume 136, Number 3, May I 1999
|
|
---|---|---|
Page(s) | 491 - 508 | |
DOI | https://doi.org/10.1051/aas:1999229 | |
Published online | 15 May 1999 |
Construction of the Tycho Reference Catalogue
1
Sternberg Astronomical Institute, Universitetsky Prosp. 13, 119899 Moscow, Russia
2
Copenhagen University Observatory, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark
3
Astronomisches Rechen-Institut, Mönchhofstrasse 12-14, D-69120 Heidelberg, Germany
4
Lund Observatory, Box 43, SE-22100 Lund, Sweden
Send offprint request to: A. Kuzmin
Received:
20
November
1998
Accepted:
10
February
1999
The Tycho Reference Catalogue (TRC) project, as proposed in 1992 by the
present authors, aimed to extend the Hipparcos reference system to fainter
magnitudes. To assure rigidity of the reference system realization, the
project relied on the Tycho Cataloguethat provides highly-accurate positions of more
than one million stars on the Hipparcos system. To maintain the precision of
the reference system over longer periods of time, high-precision proper
motions must be derived from Tycho and earlier ground-based measurements,
most notably the century-old Astrographic Catalogue(AC).
The recently published first version of the Tycho Reference Catalogue
provides highly-accurate positions and proper motions for 990 182 stars of
the Tycho Catalogue. It realizes the ICRS/Hipparcos system in the optical domain with a
median accuracy of 45 mas at epoch J2000.0. The realization is based on stars
of median magnitude mag, providing an average of 24 reference
stars per square degree. The median accuracy of the TRC proper motions,
estimated from external comparisons as 2.4 mas/yr, ensures a reference system
realization with an accuracy better than 100 mas over the time span of a few
decades. Highly-accurate astrometry combined with homogeneous two-colour
Tycho photometry makes TRC an ideal choice for a wide range of astronomical
applications.
The present paper covers the major steps of the TRC construction, including
the Astrographic Cataloguereduction onto the Hipparcos system, identification of the Tycho Catalogue
stars in the AC, derivation of proper motions, a posteriori systematic
corrections of the proper motions to account for residual AC systematic
errors, and the TRC quality assessment. The relation of the TRC with the
recently published ACT catalogue is outlined. A future version of the TRC, to
be based on the new Tycho data
processing and a global block adjustment of the Astrographic Catalogue, is briefly discussed.
Key words: astrometry / reference systems / catalogues / stars: kinematics
© European Southern Observatory (ESO), 1999