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Proper motion surveys of the young open clusters Alpha Persei and the Pleiades
In this paper we present surveys of two open clusters using photometryand accurate astrometry from the SuperCOSMOS microdensitometer. Theseuse plates taken by the Palomar Oschin Schmidt Telescope giving a widefield (5° from the cluster centre in both cases),accurate positions and a long time baseline for the proper motions.Distribution functions are fitted to proper motion vector point diagramsyielding formal membership probabilities. Luminosity and mass functionsare then produced along with a catalogue of high probability members.Background star contamination limited the depth of the study of AlphaPer to R=18. Due to this the mass function found for this cluster couldonly be fitted with a power law (ξ(m) = m-α) withα=0.86+0.14-0.19. However with the betterseperation of the Pleiades' cluster proper motion from the fieldpopulation results were obtained down to R=21. As the mass functionproduced for this cluster extends to lower masses it is possible to seethe gradient becoming increasingly shallow. This mass function is wellfitted by a log normal distribution.Complete tables from Appendix B are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/125
| UBV photometry of stars whose positions are accurately known.
Photometric indices V, B-V, and U-B were measured for about 560 stars ofthe AGK3R and NPZT catalogs between BD declinations 11 deg and 23 deg,using the 40-cm Cassegrain telescope of the Kvistaberg Observatory fromApril 1986 to May 1987. The observation procedure and the reductiontechnique were the same as in the earlier papers of this series by Oja(1984, 1985, 1986, and 1987). The mean errors were calculated from theinternal consistency of the data. The accuracy was found to be the sameas for the earlier parts of the survey.
| The Einstein shift at the eclipse of May 20, 1947, in Brazil.
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | שור |
| התרוממות ימנית: | 03h56m52.73s |
| סירוב: | +20°05'01.0" |
| גודל גלוי: | 8.784 |
| מרחק: | 188.679 פארסק |
| תנועה נכונה: | 0.8 |
| תנועה נכונה: | -13.6 |
| B-T magnitude: | 9.152 |
| V-T magnitude: | 8.815 |
קטלוגים וכינוים:
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