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Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| UBV photometric study and basic parameters of the southern open cluster NGC 2539
We present UBV photoelectric observations of 345 stars in the field ofthe southern open cluster NGC 2539. The analysis of these data allows todetermine that 169 stars are probable members of the cluster mainsequence, while 23 are possible members. The CC and CM diagrams reveal awell-defined main sequence and a populous red giant branch. We derive areddening E(B-V) = 0.06 and an apparent distance modulus V-M_v = 10.60,equivalent to a distance of 1210 pc. The age, determined by fittingisochrones computed by the Geneva group with mass loss and moderate coreovershooting, turns out to be 630 Myr, which places this cluster withinthe Hyades-age group. The isochrone for log t = 8.80 reproduces well themorphology of the upper main sequence band in the two CM diagrams,including the binary ridge. Although this isochrone also reproduces wellthe general shape of the observed red giant pattern, it appears to be alittle too bright and too red. This fact could be probably due to theuncertainty on the exact value of the mixing-length parameter. However,mass loss during the evolution of the red giants might also partiallyaccount for their location in the HR diagram. The low contamination ofthe upper main sequence of the cluster CM diagrams and its populated redgiant branch makes NGC 2539 a very good target for testing oftheoretical models. Based on observations made at Las CampanasObservatory (Chile) and at European Southern Observatory, La Silla(Chile). Table 1 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Photometric and Objective Prism Observations in Three Galactic Clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1961ApJ...134..602P&db_key=AST
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