EDP Sciences
Free access
Issue
A&A
Volume 410, Number 2, November I 2003
Page(s) 511 - 518
Section Stellar clusters and associations
DOI http://dx.doi.org/10.1051/0004-6361:20031112


A&A 410, 511-518 (2003)
DOI: 10.1051/0004-6361:20031112

Analysing the database for stars in open clusters

I. General methods and description of the data
J.-C. Mermilliod1 and E. Paunzen2, 3

1  Institut d'Astronomie de l'Université de Lausanne, 1290 Chavannes-des-Bois, Switzerland
2  Institut für Astronomie der Universität Wien, Türkenschanzstr. 17, 1180 Wien, Austria
3  Zentraler Informatikdienst der Universität Wien, Universitätsstr. 7, 1010 Wien, Austria

(Received 7 May 2003 / Accepted 25 June 2003 )

Abstract
We present an overview and statistical analysis of the data included in WEBDA. This database includes valuable information such as coordinates, rectangular positions, proper motions, photometric as well as spectroscopic data, radial and rotational velocities for objects of open clusters in our Milky Way. It also contains miscellaneous types of data like membership probabilities, orbital elements of spectroscopic binaries and periods of variability for different kinds of variable stars. Our final goal is to derive astrophysical parameters (reddening, distance and age) of open clusters based on the major photometric system which will be presented in a follow-up paper. For this purpose we have chosen the Johnson UBV, Cousins VRI and Strömgren $uvby\beta$ photometric systems for a statistical analysis of published data sets included in WEBDA. Our final list contains photographic, photoelectric and CCD data for 469 820 objects in 573 open clusters. We have checked the internal (data sets within one photometric system and the same detector technique) and external (different detector technique) accuracy and conclude that more than 97% of all investigated data exhibit a sufficient accuracy for our analysis. The way of weighting and averaging the data is described. In addition, we have compiled a list of deviating measurements which is available to the community through WEBDA.


Key words: open clusters and associations: general -- catalogs

Offprint request: E. Paunzen, ernst.paunzen@univie.ac.at

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