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Detection of a classical δ Scuti star in the new eclipsing binary system HIP 7666
HIP 7666 is a variable star newly discovered during the Hipparcosmission and classified as of unknown type (ESA 1997, The Hipparcos andTycho Catalogues, ESA SP-1200). During 23 nights between July 2000 andNovember 2000, over 2300 CCD observations in the V band were obtained.These data show that the new variable is a detached eclipsing binarysystem with an orbital period of 2.37229 days. In addition, one of thecomponents undergoes very short-period oscillations with a mainpulsation frequency of 24.46 or 25.47 c/d. HIP 7666 is therefore a newmember of the rare group of detached eclipsing binary systems with aδ Scuti type component.
| Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
| 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.
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Observation and Astrometry data
| Constellation: | Perseus |
| Right ascension: | 01h38m40.52s |
| Declination: | +52°36'23.0" |
| Apparent magnitude: | 8.987 |
| Distance: | 588.235 parsecs |
| Proper motion RA: | -0.1 |
| Proper motion Dec: | -0.4 |
| B-T magnitude: | 9.1 |
| V-T magnitude: | 8.997 |
Catalogs and designations:
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