Photometric and polarimetric analysis of the flaring activity in AE Aqr.
We present the results of simultaneous time resolved polarimetric andphotometric observations of AE Aqr carried out in 1994, July-August, atthe Crimean Astrophysical Observatory. We found that the nightly meanvalue of circular polarization can be suspected to vary from night tonight around an average value of 0.06%+/-0.01%. The interpretation ofthis result in the frame of cyclotron mechanism excludes a model ofAEAqr as a system with an accreting white dwarf. The analysis of theintrinsic magnitudes and colours of the flaring component and theabsence of noticeable variations of circular polarization in thetransition of the system from quiet to flaring state favour a thermalcharacter of the flaring radiation in the optical. The colour indices offlares are close to those of a black body with T~15000/20000K and anemitting area of S~10^20^cm^2^. This permits to conclude that the regionof flaring energy release is beyond the magnetosphere of the compactobject.
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Earth-bound observations of asteroid 19 Fortuna as support to HST imaging: lightcurves, pole direction and shape
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On the sytematic accuracy of the equatorial UBVRI standard stars
The considerable systematic difference in B-V between northern andsouthern measurements of the equatorial UBVRI standard stars arestudied. It is found that the northern data (Landolt 1983) are muchcloser to the original UBV system than the southern ones. The situationis less clear in the case of V and U-B.
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UBV photometry of HD stars in the fields of selected cataclysmic variables.
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A photometric study of the very short period eclipsing binary EH Hydrae
Recent Johnson-Cousins' B,V,Rc,Ic photoelectric observations of the veryshort period W UMa variable, EH Hya, are presented. These observationswere made, using the Yale 1M telescope and the dry-ice-cooled HamamatsuGa-As PMT at Cerro Tololo Inter-Americal Observatory. The light curvesreveal that the eclipses are total, and that the primary eclipse is anoccultation. Thus, the system is of W-type, with the larger componentbeing the cooler. Standard magnitudes were determined, and a reddeningestimate was made. A simultaneous solution of the B,V,R light curves wascomputed using the Wilson-Devinney (1971) synthetic light curve code.The solution indicates that the system consists of two late G-type starsin shallow contact with a fill-out factor of 12 percent. The differencein component temperatures is 336(8) K and the mass ratio is ratherextreme, being 0.314(2). EH Hya is compared to other very short periodbinaries of late G-type, and they are found to comprise a fairlyhomogenous group with regards to mass ratios, degree of thermal contact,and magnetic activity.
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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.
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UBV Photometry of Equatorial Stars
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Standardization of Broadband Photometry of Equatorial Standards
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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.
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A UBVRI equatorial extinction star network
An equatorial-extinction star network, based on 1503 observations of 37stars, is presented. These results together with those of Crawford etal. (1971) provide a well-determined UBVRI extinction network.Identification charts are included.
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A UBV equatorial-extinction star network
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971PASP...83..652C&db_key=AST
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INHABITED SKY
