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Tycho-2 Catalog: Catalog Help

Overview

The Tycho Catalog compiles observations by the star mapper on board the ESA Hipparcos satellite. The catalog provides astrometry (positions, parallaxes and proper motions) and two-colour photometry in B and V, for for than one million stars brighter than V=11.5 mag. The median precision (standard error) is 25 mas in position, and 0.10 mag in the B-V colour index. These values apply at the median magnitude V=10.5 for stars of median colour index B-V~0.7. The precision is greater for brighter stars, with typical errors of 7 mas in position and 0.019 mag in B-V for stars brighter than V=9 mag.

For more information, see the Hipparcos home page.

Parameters

tycho2_id
The Tycho-2 catalog number of the star.

ra
The Right Ascension of the star at the requested epoch.

dec
The Declination of the star at the requested epoch.

magb
The B-band magnitude of the star.

magv
The V-band magnitude of the star.

type
An approximate spectral type for the star, calculated from the B-V colour.

Ux
The proper motion in right ascension, in milliarcsec/yr.

Uy
The proper motion in declination, in milliarcsec/yr.

arcsec
Distance from search centre in arcsec.

Reference

Hog, E. et al., 2000, Construction and verification of the Tycho-2 Catalogue, A&A, 357, 367.
 
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