Photographicuvby photometry of the open cluster M52

Photographicuvby photometry of 15 stars in the open cluster M52 (NGC 7654) has been obtained. The distance modulusV _o–M _v=11.3±0.1 and mean cluster reddeningE(B–V)=0.57 are determined. Some basic physical characteristics of 30 stars with observeduvby values are obtained as well as a numerical estimation of the open cluster age 9.6×10⁷ yr is made.     

Multicolour photoelectric photometry of the open cluster NGC 752

In the open cluster NGC 752, 89 stars are observed in the Vilnius seven-colour photometric system, including probable members fainter than observed hitherto. Spectral classification of observed stars are made and individual reddening values are determined. The mean reddening of the cluster stars is equivalentE(B - V) = 0 _. ^m 025. By fitting on colour index-magnitude diagrams the cluster Main Sequence with the Hyades one the distance modulus (m - M)₀ = 8 _. ^m 15 ± 0 _. ^m 15 is found. For 11 red giant members of the cluster absolute magnitudes are derived and compared with ones of the standard calibration. It is obtained that the cluster giants are in mean 0 _. ^m 6 fainter than giants of corresponding spectral class in the solar vicinity.     

Photoelectric photometry of JV

UBV photometry of JV near greatest western elongation shows this satellite to be about one magnitude fainter than previously believed. It is observed to be very red, having a B-V color index near +1.5 mag. Unlike the Galilean satellites, JV appears to bea low-albedo object.     

CCD BV photometry of the old rich open cluster king 2

We present preliminary results of CCD BV photometry of the old open cluster King 2. The values obtained for the main parameters are:E(B-V)=0.31, (m-M)₀=13.78, metal content approximately solar, and age 6×10⁹ yr. From the comparison with synthetic colour-mgnitude diagrams generated by models with overshoot we try to answer the question whether or not convective elements generated in the core can penetrate into the surrounding stable zone (separated by a discontinuity of molecular weight).Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

CCD uvbyβ photometry of the young open cluster NGC 663

NGC 663 is a young, moderately rich open cluster, known to contain one of the largest fractions of Be stars among all galactic clusters. In this work we present CCD u v by β photometry for stars in its central area. We have used these data to obtain the main cluster physical parameters. We find that the reddening is highly variable, with values ranging from   E ( b − y ) = 0.639 ± 0.032  in the central part to   E ( b − y ) = 0.555 ± 0.038  in the south-east. The distance modulus is found to be  11.6 ± 0.1 mag (2.1 kpc)  and the age  log  t = 7.4 ± 0.1 yr (25⁺⁷₋₅ Myr)  . The age obtained is consistent with the interpretation of the Be phenomenon as an evolutionary effect.     

Photoelectric photometry of 21 asteroids

Photoelectric lightcurves of 21 asteroids are presented. The observations were carried out from 1978 to 1982 at the Astronomical Observatory of Torino (at the Astrophysical Observatory of Catania for 137 Meliboea). For 10 objects a reliable rotation period has been obtained, while for two others a rough estimate is given. In several cases the analysis of the observed amplitudes versus the ecliptic longitudes indicates the most favorable future oppositions for period and/or pole determination. For some asteroids transformations to UBV Standard System were performed.     

Photoelectric photometry of 17 asteroids

Seventeen asteroids were observed photoelectrically in the V band at the Torino Observatory in 1983–1984 as part of the coordinated campaign for pole determinations. The obtained lightcurves allowed us to deduce new pole coordinates of four objects, while for the other three a check of previous results was possible. Additionally, the ambiguity for the rotation period of 776 Berbericia was solved in favor of a shorter value, and the importance of this problem was evidenced once more after analyzing the lightcurves of 69 Hesperia and 349 Dembowska. A new possible value of the period of 121 Hermione was also suggested.     

Photoelectric photometry of 14 asteroids

Results of observations of 14 asteroids are reported; all of them, except 181 Eucharis, have been previously observed at least once. V photoelectric lightcurves were obtained from September 1982 to June 1983 at the Astronomical Observatory of Torino and at the Astrophysical Observatory of Catania. Part of this program aims to obtain complete lightcurves and, when possible, phasecurve information and to determine amplitudes and V magnitudes at different longitudes for a selected group of asteriods, in order to enlarge the set of known rotational axis directions.     

Photoelectric photometry of Z herculis

Two-colour light curves of Z Her were obtained observing the system from 1978 to 1981. The wave-like distortion at outside eclipses were derived. The amplitudes of the wave increase and its minimum migrates towards the decreasing orbital phase with a period of about 1.4 yr. An attempt was made to represent the wave-like distortions with a truncated Fourier series. The representation was found to be unsatisfactory since the distribution of the present observations is not regular but forms separate groups along the time axis. Therefore, further observations to cover the phases evenly in between the minima are needed.     

Near-infrared time-series photometry of six fields in the young open cluster IC 2391

Fields containing targets of spectral types later than M5 were monitored in   JHK_s   for about 7 h each. None of the targets showed variability at levels exceeding 0.02 (or smaller, in some cases). Seven new variable stars were discovered serendipitously. The large number of measurements (more than 50) of each field allows the construction of accurate colour–magnitude and colour–colour diagrams. These could be used to identify a small number of candidate very cool objects.     

Photoelectric photometry of V541 cassiopeiae

We give the results of two-colour photoelectric photometry of V541 Cas made in 1982 Sept-Dec. Using the Wilson-Devinney method, we obtained a photometric solution which showed the system to be a detached binary, with a mass ratio 2.083, and the less massive component filling its Roche lobe more closely. Its light curve is very similar to those of AT and AZ Cam.     

Photoelectric photometry of the peculiar system RT Lacertae

The observations of the peculiar eclipsing binary RT Lac were continued during the observing seasons of 1982 and 1983. The salient properties of the light curves were presented. The shallowest primary eclipse was observed in 1983. When the light curves, obtained in six years sucessively, are interpreted together it is seen that the variations of the brightness at mid-primary and second maximum are too similar to each other. The colour variations at mid-primary also follow those variations in the brightness. These circumstances indicate that the starspot hypothesis is insufficient alone to explain all the phenomena observed. The earlier spectral type G9 companion may be intrinsically variable and the unusual distortion on the light curves following the secondary eclipse may arise from the gas-stream from larger K star to the G9 star.     

Photoelectric photometry of the eclipsing binary EE Aqr

The system EE Aqr has been observed inUBV colours. A consistent set of orbital elements and a slightly improved period of 0 _. ^d 5089954 have been obtained. The eclipse is partial and variability is of Lyrae-type. The colour of the components has been determined.     

CCD photometry of W UMa-type contact binaries in the old open cluster Berkeley 39

We present the combined BVI multicolor photometric solutions of seven EW variables in the old open cluster Berkeley 39.The observations were carried out in the B and V passbands from the 2 m telescope at the IUCAA-Girawali Observatory in India.The analysis is done using the 2003 version of the Wilson-Devinney code and the fitted light curves are presented.The light curves appear to be symmetric in all the passbands.The photometric solutions suggest that the variables are W-type systems.The new ephemeris ind...     

Photoelectric photometry of the eclipsing binary WX Cancri

We obtained 672 observed points in yellow and 674 in blue in our photoelectric light curve of the Algol-type binary WX Cnc and we give 2 each of the times of primary and secondary minima. Using the Russell-Merrill method, we derived four mutually consistent sets of orbital elements, and determined the spectral type to be F6V for the combined system, and F5V and F8V for the primary and secondary components, separately. We found WX Cnc to be a detached system of two main sequence stars.     

Photoelectric photometry of AR Lac in 1982

In this paper we present the observations of AR Lac, which were obtained in 1982. The variations in the light curves, occurred in the time interval as short as two months, indicated that the system was very active in 1982 like in 1979. The times of the minima obtained in this study indicate that the orbital period of the system continues to decrease. The decrease in the period was recalculated using all the times of minima obtained photoelectrically between 1961 and 1982 and found to be 17.0±1.4 s century^?1.