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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
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| Catalogue of blue stragglers in open clusters.
An extensive survey of blue straggler candidates in galactic openclusters of both hemispheres is presented. The blue stragglers wereselected considering their positions in the cluster colour-magnitudediagrams.They were categorized according to the accuracy of thephotometric measurements and membership probabilities. An amount of 959blue straggler candidates in 390 open clusters of all ages wereidentified and classified. A set of basic data is given for everycluster and blue straggler. The information is arranged in the form of acatalogue. Blue stragglers are found in clusters of all ages. Thepercentage of clusters with blue stragglers generally grows with age andrichness of the clusters. The mean ratio of the number of bluestragglers to the number of cluster main sequence stars is approximatelyconstant up to a cluster age of about 10^8.6^ yr and rises for olderclusters. In general, the blue stragglers show a remarkable degree ofcentral concentration.
| Stromgren photometry of open clusters. I - NGC 6281, NGC 6405
Stromgren indices for A-type and B-type stars in the southern openclusters, NGC 6281 and NGC 6405, are presented. Their membership isdiscussed and the reddening of the clusters is estimated. It is shownthat shifting of the main sequence to the standard relation of Crawford(1975, 1978, 1979) yields a reddening of E(b-y) = 0.120 for NGC 6281 anda reddening of E(b-y) = 0.110 for NGC 6405. The occurrence of a CP1(Am)and a Delta-Sct star in NGC 6405 is considered. The results of theStromgen photometry are given in tables.
| Evidence of decay of the magnetic fields of AP stars
Data obtained in the Geneva photometric system (Rufener, 1981) andappropriate calibrations of this system in terms of surface magneticfield and gravity are used to provide, on the basis of 708 field andcluster Ap stars, observational evidence that these stars undergo decayof their magnetic field on an evolutionary timescale. Justifications aregiven for the application of a photometric gravity calibration topeculiar stars. The dependence of the photometrically estimated surfacemagnetic field on gravity is found to differ markedly from availabletheoretical calculations. HgMn stars are found to show the same trend,strengthening the impression that they might be slightly magnetic.He-weak stars do not.
| Photoelectric search for CP2-stars in open clusters. V - NGC 6281, NGC 6405, IC 4665
130 stars in the medium age clusters NGC 6281, NGC 6405, and IC 4665were observed by photoelectric photometry in the Delta a-system(Maitzen, 1976) in order to detect CP2-peculiarity by the presence ofthe lambda 5200 depression feature. No CP2-star was found in IC 4665,one in NGC 6281, and 3 in NGC 6405. Star No. 77 of NGC 6405 exhibits thestrongest lambda 5200 depression ever measured by this type ofphotometry. The (very small) reddening correction of the a-values isdiscussed and found to agree well with previous papers of this series.
| Photometry of stars near 3U 1700-37= HD 153919 and 3U 0900-40=HD 77581.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..339B&db_key=AST
| The open cluster NGC 6281
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974PASP...86..284F&db_key=AST
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Pozíciós és asztrometriai adatok
| Csillagkép: | Skorpió |
| Rektaszcenzió: | 17h04m36.37s |
| Deklináció: | -37°54'27.1" |
| Vizuális fényesség: | 9.042 |
| RA sajátmozgás: | -2.6 |
| Dec sajátmozgás: | -1.7 |
| B-T magnitude: | 9.09 |
| V-T magnitude: | 9.046 |
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