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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.
| The Gamma DOR variable HD 164615 - Results from a multisite photometric campaign
We present the results from a multisite photometric campaign devoted tothe Gamma Dor variable HD 164615. During the campaign, data werecollected in the Johnson and Stromgren photometric systems. A firstsearch for sinusoidal periodicities yielded a three-term solution withfrequencies f1 = 1.2328, f2 = 1.0899, and f3 = 2.3501/d, and a long-termtrend f4 = 0.1301/d. The star may therefore be multiperiodic with eachfrequency related to a pulsation mode. However, a further examination ofthe curve provided evidence that the amplitude at the instant of maximumbrightness is modulated. Alternatively, HD 164615 may be a monoperiodicvariable with frequency f1 = 1.2321/d, showing amplitude modulation withfrequency f4 = 0.1301/d. The presence in the power spectra of thecoupling terms f2 = f1 - f4 and f3 = f1 + f4 - 1 supports the latterinterpretation. In the monoperiodic case the previously giveninterpretation based on a spot carried through the visible disk byrotation still holds, provided that the spot is bright and evolves on atime scale of a few days. However, similarities with other Gamma Dorstars provide indirect indication in favor of the existence of anonradial pulsation interpretation.
| Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
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Observation and Astrometry data
| Constellation: | Altar |
| Right ascension: | 17h59m26.91s |
| Declination: | -47°46'26.7" |
| Apparent magnitude: | 8.084 |
| Distance: | 355.872 parsecs |
| Proper motion RA: | 9.4 |
| Proper motion Dec: | -21.2 |
| B-T magnitude: | 9.195 |
| V-T magnitude: | 8.176 |
Catalogs and designations:
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