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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.
| Interstellar reddening in the Southern Hemisphere. I - The UVBY beta observations
The uvby-beta photometric data obtained from a Southern Hemisphereobservational project is presented. A uvby-beta photometric network ofnearly 3900 A and early F stars has been established with the intentthat the stars serve as 'space probes' for measurements of interstellarreddening.
| Estimation of spectral classifications for bright southern stars with interesting Stromgren indices
This paper investigates the degree of success with which uvby photometrycan be applied to predict spectral classifications for 947 A, F, and Gstars brighter than an apparent magnitude of 8.3 and with four-colorindices indicating some kind of interesting, unusual, or peculiarspectrum. One or several possible spectral classifications are estimatedfor each star from photometry alone, double stars are distinguished, andthe estimates are compared with published classifications. The resultsshow that the framework provided by uvby photometry can be extended toinclude most G and K stars, reddened stars, peculiar stars, and certaintypes of double star.
| On the decline stage of Nova V 3888 SGR /1974/
Photoelectric UBV and uvby photometry of V 3888 SgrNova Sgr 1974 wasobtained covering 25 days of its decline stage. The light curve and thecolor variations are described and compared with the spectrum. V 3888Sgr seems to be a fast nova with a slightly abnormal light curve showinga rapid early decline but an extended transition state. Its maximumbrightness is estimated to be about 7.5 m, its amplitude not less thanabout 13.5 and its distance 3.5 kpc.
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Observation and Astrometry data
| Constellation: | Sagittarius |
| Right ascension: | 17h47m27.09s |
| Declination: | -18°06'25.6" |
| Apparent magnitude: | 7.554 |
| Distance: | 137.363 parsecs |
| Proper motion RA: | 7.8 |
| Proper motion Dec: | -4 |
| B-T magnitude: | 7.888 |
| V-T magnitude: | 7.582 |
Catalogs and designations:
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