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Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over a longinterval of time and summarized mainly in the FK5. Part III of the FK6(abbreviated FK6(III)) contains additional fundamental stars with directsolutions. Such direct solutions are appropriate for single stars or forobjects which can be treated like single stars. Part III of the FK6contains in total 3272 stars. Their ground-based data stem from thebright extension of the FK5 (735 stars), from the catalogue of remainingSup stars (RSup, 732 stars), and from the faint extension of the FK5(1805 stars). From the 3272 stars in Part III, we have selected 1928objects as "astrometrically excellent stars", since their instantaneousproper motions and their mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,354 of the stars in Part III are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives, in addition to the SI mode, the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(III) proper motion in the single-star mode is 0.59 mas/year. This isa factor of 1.34 better than the typical HIPPARCOS errors for thesestars of 0.79 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(III) proper motions have atypical mean error of 0.93 mas/year, which is by a factor of about 2better than the corresponding error for the HIPPARCOS values of 1.83mas/year (cosmic errors included).
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| Improved Mean Positions and Proper Motions for the 995 FK4 Sup Stars not Included in the FK5 Extension
Not Available
| UBV photometry of stars whose positions are accurately known. VI
Results are presented from UBV photometric observations of 1000 stars ofthe Bright Star Catalogue and the faint extension of the FK5.Observations were carried out between July 1987 and December 1990 withthe 40-cm Cassegrain telescope of the Kvistaberg Observatory.
| Photometric variability in chromospherically active stars. III - The binary stars
Differential UBV photometry of 49 late-type chromospherically activebinary stars has been obtained. A total of 12,353 differential UBVmagnitudes have been acquired and are used to determine seasonalphotometric periods, amplitudes, mean brightnesses, maximum spotamplitudes, 'unspotted' differential magnitudes, and times of minimumlight. Standard Fourier techniques are used to investigate the cause ofthe light variability. Eight stars are found which exhibit lightvariations due not to spot activity but rather to ellipticity and/orreflection effect. Others show combinations of all three effects. Someof the systems also show substantial differences between theirrotational and orbital period.
| E. W. Fick Observatory stellar radial velocity measurements. I - 1976-1984
Stellar radial velocity observations made with the large vacuumhigh-dispersion photoelectric radial velocity spectrometer at FickObservatory are reported. This includes nearly 2000 late-type starsobserved during 585 nights. Gradual modifications to this instrumentover its first eight years of operation have reduced the observationalerror for high-quality dip observations to + or - 0.8 km/s.
| Photometric observations of RS Canum Venaticorum stars
Photometric observations of the following RS CVn stars are presented anddiscussed: HR 3 (33 Psc), HR 373 (39 Cet), LX Per, HR 4374 (53 UMa), HR4665, HR 7275, HK Lac, HR 8448 (AR Lac), HR 8575, HR 8703 and SZ Psc.Observations of HR 3 and HR 8448 are fragmentary. HR 4374 is notphotometrically variable. For the other stars, the range, phase andshape of the photometric distortion wave have been determined.
| Four years of photometry of DK Draconis = HR 4665
Differential BV photometry of the K0 III + K0 III long-period RSCVn-type binary DK Dra = HR 4665 in 1977, 1978, 1979, and 1980 at eightdifferent observatories is presented. A least squares fit to times ofmaximum and minimum light yields the ephemeris JD = 2,443,219.5 + 63.75d E for times of minimum. This photometric period is 1% shorter than thespectroscopically determined orbital period 64.44 d. The light curve wassymmetrical and roughly sinusoidal in 1979 and 1980 but was asymmetricalin 1977 and 1978, with a faster rise to maximum. During these four yearsDK Dra varied between V = 6.07 and 6.35 m.
| Evidence for starspots on DK Draconis /HR 4665/
Observations of the long-period RS CVn-type binary DK Dra from Februarythrough September 1978 are presented. Light variations appear to bequasisinusoidal with a period of 64.6 + or - 0.4 d, and cycle-to-cyclechanges in the character of the light curve have most likely occurred.No evidence of H-alpha or O I emission is found. A starspot model isused to generate theoretical light curves which fit those observed.Results indicate that the minimum spotted area is about 8% of thestellar surface area, which suggests that the fractional spotted area isat least 40-80 times greater for DK Dra than the total fractional areaon the sun at sunspot maximum. An analysis of multibandpass data showsthat the temperature difference between the photosphere and spot isabout 1100 K.
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Osservazione e dati astrometrici
| Costellazione: | Dragone |
| Ascensione retta: | 12h26m24.20s |
| Declinazione: | +71°55'47.0" |
| Magnitudine apparente: | 6.24 |
| Distanza: | 119.332 parsec |
| Moto proprio RA: | -149.9 |
| Moto proprio Dec: | -22.9 |
| B-T magnitude: | 7.642 |
| V-T magnitude: | 6.441 |
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