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The B jRI Photometric System
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS...99..281G&db_key=AST
| V803 Aquilae: A newborn W Ursae Majoris Siamese twin?
A complete photometric analysis of BVRI photometry of the physicallycompact, eclipsing binary V803 Aquilae is presented. Six mean epochs ofminimum light were determined from observations covering three primaryand three secondary eclipses. A period study covering 54 years ofobservation or nearly 77,000 orbital revolutions reveals three distincteras of constant period with two major period jumps of +0.1 s and -0.3s. The light curves shows that the primary and secondary eclipse depthsare identical in V, and are nearly identical in B, R, and I, indicatingthat the components have nearly the same temperatures. Standardmagnitudes were determined and a reddening estimate was made. Asimultaneous solution of the four light curves was computed using theWilson-Devinney synthetic light-curve code. The solution indicates thatthe system consists of twin approximately K4 stars in shallow contactwith a fill-out of approximately 8%. A mass ratio of 1.000 was computedwith a negligible temperature difference of only 6 K. Thus, based on ourpurely photometric solution, V803 Aql is made up of 'Siamese' (contact)twin components. Theory would indicate that the twins have just recentlycome into contact, and the lack of other equal-mass W Ursae Majorissystems would indicate that it is in a very transient or unusual state.
| Photometric investigation of a very short period W UMa-type binary - Does CE Leonis have a large superluminous area?
A complete photometric analysis of BVRI Johnson-Cousins photometry ofthe high northern latitude galactic variable, CE Leo is presented. Theseobservations were taken at Kitt Peak National Observatory on May 31,1989-June 7, 1989. Three new precise epochs of minimum light weredetermined and a linear and a quadratic ephemeris were computed fromthese and previous data covering 28 years of observation. The lightcurves reveal that the system undergoes a brief 20 min totality in theprimary eclipse, indicating that CE Leo is a W UMa W-type binary. Asystemic velocity of about -40 km/s was determined. Standard magnitudeswere found and a simultaneous solution of the B, V, R, I light curveswas computed using the new Wilson-Devinney synthetic light curve codewhich has the capability of automatically adjusting star spots. Thesolution indicates that the system consists of two early K-type dwarfsin marginal contact with a fill-out factor less than 3 percent. Evidencefor the presence of a large (45 deg radius) superluminous area on thecooler component is given.
| UBV(RI)c photometry of equatorial standard stars - A direct comparison between the northern and southern systems
UBV(RI)c photometry of 212 stars from Landolt's list of equatorialstandards is presented. The observations are tied to the system definedby Cousin's E-region standards. A comparison of the present results withLandolt's reveals reasonably good agreement for (V-R)c and (V-I)c, butmarked systematic differences for (B-V) and (U-B). The UBV systems ofCousins and Landolt are evidently not the same and both probably differfrom Johnson's original system.
| Photoelectric observations of classical cepheids.
Not Available
| Hard X-ray pulse profile and period evolution of AO535 + 26 and GX 1 + 4 as observed by the Franco-Soviet Signe satellite experiments
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1986ApJ...310..773R&db_key=AST
| UBVRI photometric standard stars around the celestial equator
It is pointed out that accurate, internally consistent, and readilyaccessible standard star photometric sequences are necessary for thecalibration of the intensity and color data which astronomers obtain atthe telescope. The photometric results provided in connection with thepresent study represent the first part of an effort which is concernedwith the presentation of UBVRI photoelectric photometric standard starsin the magnitude range from 7 to 17 over as broad a range in color aspossible. All of the photometric observations were made with a 31034type photomultiplier used in a pulse counting mode. Some 15 to 25standard stars chosen from Cousins' lists (1973, 1976) in the E-regionswere observed with an 0.4-m telescope each night along with the programstars. UBVRI standard stars were observed periodically throughout thenight. Observations with a 0.9-m telescope were also conducted. TheUBVRI photoelectric observations take into account 223 stars.
| Distances to eclipsing binaries. III - Masses, radii, and absolute magnitudes of 96 stars
Distances to, and absolute magnitudes of, 96 components of eclipsingbinaries with well-determined absolute dimensions have been computedusing V-R photometry. The calculations take into account interstellarreddening, which is estimated from existing UBV and uvby-betaphotometry, as well as photometric proximity effects. The resultingabsolute magnitudes, dimensions, and masses are compared with zero-agemain sequences predicted by theory. Theory is in good agreement with theobserved data for stars more massive than the sun if a composition (X,Y, Z) = (0.66 + or - 0.03, 0.303 + or - 0.03, 0.037 + or - 0.005) ischosen. The corresponding helium-to-hydrogen number ratio is 0.115 + or- 0.02, in agreement with previous estimates.
| Spectral classifications for Landolt's celestial equatorial standard stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979AJ.....84..783D&db_key=AST
| A set of faint equatorial standard stars for BVRI photometry
BVRI photoelectric photometry is presented for 48 of Landolt's (1973)faint equatorial standard stars. The 48 stars, which have spectral typesfrom A to K and V magnitudes in the range from 8.0 to 12.0, are chosento provide two blue and two red stars in each of 12 of the equatorialselected areas studied by Landolt. The program stars were observed withan S-1 photomultiplier, with the B-V, V-R, and V-I colors transformed tothe Johnson system; they were also observed with an RCA 31034Aphotomultiplier, with the resulting V-R and V-I colors given on azero-point-adjusted instrumental system. Observations of several Mdwarfs with the two photomultipliers are also reported. Serious problemsencountered in transforming the observed V-R and V-I colors of the Mdwarfs to the Johnson system are discussed.
| Equatorial UBVRI photoelectric sequences
From 1335 BVRI observations of 189 stars in selected areas 92-115,Landolt's (1973) network of faint UBV standards has been extended to RI. Of these stars, 173 have four or more observations. The (U-B) valuesof Landolt are adopted, and a well-observed equatorial faint-starnetwork is presented on the Johnson UBVRI photometric system.
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Datos observacionales y astrométricos
| Constelación: | Águila |
| Ascensión Recta: | 19h37m04.48s |
| Declinación: | +00°37'31.9" |
| Magnitud Aparente: | 9.774 |
| Movimiento Propio en Ascensión Recta: | 1.3 |
| Movimiento Propio en Declinación: | -3.7 |
| B-T magnitude: | 9.879 |
| V-T magnitude: | 9.783 |
Catálogos y designaciones:
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