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Astron. Astrophys. 345, 471-484 (1999)

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Open clusters with Hipparcos *

I. Mean astrometric parameters

N. Robichon 1,2, F. Arenou 2, J.-C. Mermilliod 3 and C. Turon 2

1 Sterrewacht Leiden, Postbus 9513, 2300 RA Leiden, The Netherlands
2 Observatoire de Paris, section de Meudon, DASGAL/CNRS URA 335, F-92195 Meudon CEDEX, France (Noel.Robichon, Frederic.Arenou, Catherine.Turon@obspm.fr)
3 Institut d'Astronomie de Lausanne, CH-1290 Chavannes des Bois, Switzerland (Jean-Claude.Mermilliod@obs.unige.ch)

Received 9 December 1998 / Accepted 19 February 1999


New memberships, mean parallaxes and proper motions of all 9 open clusters closer than 300 pc (except the Hyades) and 9 rich clusters between 300 and 500 pc have been computed using Hipparcos data. Precisions, ranging from 0.2 to 0.5 mas for parallaxes and 0.1 to 0.5 mas/yr for proper motions, are of great interest for calibrating photometric parallaxes as well as for kinematical studies. Careful investigations of possible biases have been performed and no evidence of significant systematic errors on the mean cluster parallaxes has been found. The distances and proper motions of 32 more distant clusters, which may be used statistically, are also indicated.

Key words: stars: distances – Galaxy: open clusters and associations: general

* Based on observations made with the ESA Hipparcos astrometry satellite

Send offprint requests to: Noïl Robichon

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© European Southern Observatory (ESO) 1999

Online publication: April 19, 1999