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Multicolour CCD measurements of visual double and multiple stars. III
Context: Recent CCD observations were performed in the period 1998-2004for a large sample of visual double and multiple stars selected from theHipparcos Catalogue and/or from the Gliese Catalogue of Nearby Stars. Aims: Accurate astrometric and photometric data allowing us tocharacterise the individual components are provided. These data arecompared to Hipparcos data or to data from an older epoch to assess thenature of the observed systems. Methods: We simultaneously apply aMoffat-Lorentz profile with a similar shape to all detected componentsand adjust the profile parameters from which we obtain the relativeastrometric position (epoch, position angle, angular separation) as wellas differential multi-colour photometry (filters (B)VRI). Results: Wethus acquired recent data for 71 visual systems of which 6 are orbitalbinaries, 27 are nearby, and 30 are multiple systems. In three of thesecases, the systems remained unresolved. 23 new components were detectedand measured. Two new visual double stars of intermediate separationwere also found. The estimated accuracies in relative position are0.04° and 0.01 arcsec respectively, while those in differentialphotometry are of the order of 0.01-0.02 mag in general. Conclusions:.The nature of the association of 55 systems is evaluated. New basicbinary properties are derived for 20 bound systems. Component coloursand masses are provided for two orbital binaries.Based on observations collected at the National AstronomicalObservatory, Rozhen, and the Astronomical Observatory, Belogradchik,both operated by the Institute of Astronomy, Bulgarian Academy ofSciences. Also based on data obtained by the Hipparcos astrometrysatellite. Appendix A is only available in electronic form athttp://www.aanda.org Tables 4-6 are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/464/641
| A photometric monitoring of bright high-amplitude delta Scuti stars. II. Period updates for seven stars
We present new photometric data for seven high-amplitude delta Scutistars. The observations were acquired between 1996 and 2002, mostly inthe Johnson photometric system. For one star (GW UMa), our observationsare the first since the discovery of its pulsational nature from theHipparcos data. The primary goal of this project was to update ourknowledge on the period variations of the target stars. For this, wehave collected all available photometric observations from theliterature and constructed decades-long O-C diagrams of the stars. Thistraditional method is useful because of the single-periodic nature ofthe light variations. Text-book examples of slow period evolution (XXCyg, DY Her, DY Peg) and cyclic period changes due to light-time effect(LITE) in a binary system (SZ Lyn) are updated with the newobservations. For YZ Boo, we find a period decrease instead of increase.The previously suggested LITE-solution of BE Lyn (Kiss &Szatmáry \cite{Kiss95}) is not supported with the new O-Cdiagram. Instead of that, we suspect the presence of transient lightcurve shape variations mimicking small period changes.
| Simultaneous UVBY beta photometry of SX Phoenicis stars
In this paper, we present simultaneous uvby beta photometricobservations of five SX Phe stars: XX Cyg, CY Aqr, DY Peg, BS Tuc, andSU Crt. The light curves were obtained at Sierra Nevada Observatory,Granada, Spain and European Southern Observatory, La Silla, Chile on 30nights from 1986 through 1988 and contain 847 points in each of the fouruvby colors of the Stromgren photometric system and 542 points in eachof the two narrow and wide channels of the H-beta Crawford system.
| Analysis of Neckel and Chini standard stars in the UBVRI photometric system
This paper studies the list of 60 faint standard stars of Neckel andChini (1980) in the UBVRI Johnson photometric system. We have re-reducedthe standard stars using our own method of reduction from a large numberof selected observations made at the Observatorio Astronomico Nacionaland at the Centro Astronomico Hispano-Aleman, both at Calar Alto, Spain,and at the Observatorio del Roque de los Muchachos, La Palma Island,Spain. The reduction method used is explained and the results are givenfor the four colors used: (B-V), (U-B), (V-R), and (V-I), together withthe V magnitude, that is, we have corrected many standard stars for eachcolor and magnitude. These results are supported with graphs whereresidual color is plotted against corresponding color (or magnitude).Finally, our (V-R) and (V-I) results are compared to those of Taylor etal. (1989), with a good correspondence.
| The properties of the Neckel-Chini VRI system
Cousins (1980) data for 54 of the standard stars of Neckel and Chini(1980) and published measurements are used to investigate the propertiesof the Neckel-Chini VRI system. For red stars, this system diverges fromthe Johnson (1962) system, despite frequent claims of identity betweenthe two. The Neckel-Chini and Cousins systems, however, are closelycomparable. Both of these conclusions were previously reached in a paperby Bessell (1983); fair to good quantitative agreement with his resultsare obtained. Reddening ratios, the scatter in the Neckel-Chinistandard-star data, and the effect of this scatter on publishedmeasurements for program stars, are discussed. Transformations from theNeckel-Chini system to the Cousins system are given.
| The Baade-Wesselink method applied to field RR Lyrae stars. I - UBVRI photoelectric and radial velocity data
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987A&AS...69..135C&db_key=AST
| Investigation and experimental observations on the two-channel stellar electrophotometer
Sample data from test observations obtained with the two-channeldifferential stellar electrophotometer (Kakhiani and Makariev, 1982;Kakhiani, 1982) on the 125-cm telescope at Abastumani AstrophysicalObservatory are presented graphically and discussed. The photometerpermits real-time simultaneous measurement of two stars in the 22 x22-arcmin field of the telescope with exposure time 0.0001-100 sec andrms deviation of 0.005-0.02 mag in the range 10-13.5 mag. Light curvesfor DY Peg and GD 428 show good agreement with published data anddemonstrate the high gain, time resolution, and accuracy of thephotometer.
| Sixty faint UBVRI standards
A list of 60 faint UBVRI standards is presented. Their UBV magnitudesare in the system introduced by Johnson (1955) and their V-R and V-Icolors are in the system of the Arizona Tonantzintla catalogue byIriarte et al. (1965). These stars are spread over an equatorial belt atan angle less than 30 deg, so that they can be observed as well fromnorthern as from southern sites.
| A two-colour photometry of the short period RR Lyrae star DY Peg
Abstract image available at:http://adsabs.harvard.edu/abs/1975A&AS...21..183G
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Пегас |
| Прямое восхождение: | 23h09m05.05s |
| Склонение: | +17°08'20.7" |
| Видимая звёздная величина: | 9.941 |
| Собственное движение RA: | 14.5 |
| Собственное движение Dec: | -7.9 |
| B-T magnitude: | 10.518 |
| V-T magnitude: | 9.989 |
Каталоги и обозначения:
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