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The improvement of the star positions of the Potsdam PZT catalog
Regular determinations of the right ascension and declination of starswith the aid of a photographic zenith tube (PZT) were begun in ageodetic-astronomical observatory of the German Democratic Republic in1972. Results obtained during the years 1972 and 1973 were used for afirst improvement of stellar positions listed in the Third Catalog(Katalog) of the 'Astronomische Gesellschaft' (Astronomical Society)AGK3. The corrections resulted in a distinct improvement of the accuracyof the positional values. However, the possibility could not be excludedthat the results were still affected by remaining errors with systematiccharacteristics. In order to eliminate the considered deficiencies, newstellar coordinate corrections were computed on the basis of aconsiderably larger data set. The new catalog containing the reviseddata has been called PZT 80, while the data obtained on the basis of thefirst observations are listed in PZT 74. The new catalog is presented inthe appendix.
| A classification of Be stars
Based upon a sample of 140 stars observed over 20 years for which about5,000 spectrograms are available, a classification scheme of Be stars ispresented. This is the first attempt to subdivide the Be star group intophysically significant subgroups, from which typical objects can beselected for further study. The four groups proposed are based upon adiscussion of spectrum characteristics, multicolor photometry,polarization, rotational velocities, UV spectral types and timevariability. Starting with the group membership of a Be star,predictions can be made of the future behavior of it.
| Bright Late M-Type Stars Near the Galactic Equator.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1954ApJ...120..118N&db_key=AST
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Member of following groups:
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Observation and Astrometry data
| Constellation: | はくちょう座 |
| Right ascension: | 21h52m02.40s |
| Declination: | +52°42'30.8" |
| Apparent magnitude: | 9.085 |
| Proper motion RA: | 4.4 |
| Proper motion Dec: | 1.7 |
| B-T magnitude: | 9.133 |
| V-T magnitude: | 9.089 |
Catalogs and designations:
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