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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
| Absolute Tilt from a Laser Guide Star: A First Experiment
Absolute tip-tilt recovery using a tilt signal measured on a Laser GuideStar is a central problem in the framework of the development ofAdaptive Optics Systems reaching full sky coverage down to visiblewavelengths. In the past few years, various techniques aimed at solvingthis problem have been proposed. However only a couple of these has beenrecently tested in practice. We report about an experiment aimed atevaluating the performance of one of these techniques called the`Elongation Perspective' technique. Our experiment has been performedusing the ALFA system in Calar-Alto (Spain) and involves thesimultaneous operation of the 3.6 m and the 2.2 m telescopes at theObservatory. This article describes the telescope configuration used, aswell as the data reduction process carried out in order to estimate thescientific object tilt. The technique performances are discussed interms of the residual tilt error variance and related correlationcoefficient. The analysis shows that, despite the low SNR of ourmeasurements, the atmospheric tilt variance is reduced to 80% of itsinitial value corresponding to a correlation coefficient of about 0.6.To get a better estimate of the performance achievable using thistechnique, the tilt error variance due to photon noise in the lasermeasurement is estimated and removed from the obtained tilt errorvariance. When this correction is done, this variance is reduced toabout 50% of its initial value, showing that the use of this techniquecan give rise to a significant reduction of the scientific object imagemotion.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| Photometric studies of northern galactic clusters. I. Roslund No. 5.
Abstract image available at:http://adsabs.harvard.edu/abs/1971AJ.....76..464L
| Etude pour chaque champ de l'absorption et de la repartition des vitesses radiales EN fonction de la distance.
Not Available
| La mesure des vitesses radiales au prisme objectif. VII - 2e liste de vitesses radiales déterminées au prisme objectif à vision directe
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 20h08m12.71s |
| Declinazione: | +33°24'32.4" |
| Magnitudine apparente: | 8.1 |
| Distanza: | 259.067 parsec |
| Moto proprio RA: | 7 |
| Moto proprio Dec: | 1.1 |
| B-T magnitude: | 9.467 |
| V-T magnitude: | 8.213 |
Cataloghi e designazioni:
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