Photoelectric observations of BV Draconis

In this paper the twoB andV light curves of the close eclipsing binaryBV Draconis, obtained with the 48-in reflector of the National Observatory of Athens, are represented and discussed. Also, new period of the system is given.     

Photoelectric and visual observations of AM Cas

According to statistical informations the orbital period of this cataclysmic binary of Z Camelopardalis type should be in the range between 0^d.10 and 0^d.19. A sole deep minimum was found photoelectrically. It lasted about 40 minutes and had an amplitude of nearly 2 mag in U. For reasons described in detail it can hardly be interpreted as an eclipsing one. Possibly there is no contribution to the light variation of AM Cas from orbital motion.     

Photoelectric observations of the eclipsing binary U Pegasi

Photoelectric observations inB andV of the eclipsing binary U Pegasi, made during 1980 with the 48 in. reflector of the National Observatory of Athens, are presented and discussed. The light curve seems to have remained constant since 1958 while the period of the system continues to decrease.     

Photoelectric observations of Fexiv coronal depletion: 20 April 1976

On 20 April 1976 a coronal emission line transient was observed on the west limb of the Sun using a 5303 Fexiv detection system and the Sacramento Peak Observatory's 40 cm coronagraph. The transient as observed at a single sample point, and the time scale for this event was found to be about 40 min. Limb scans before and after the event are used to estimate the amount of coronal mass involved in this relatively slow event. A depletion of the inner corona of 4.4 × 10³⁸ electrons (8.8 × 10¹⁴ G) is inferred by differencing pre- and post-event model electron density distributions.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

Photoelectric monitoring of a shell star in perseus

We report on the 3-colour photoelectric monitoring of the shell star in Perseus, discovered in 1978, [1]. On the night of 1983 Feb 4–5, this star still showed obvious light variations, though the amplitude was less than in 1979. On the next night, the light variation was close to the observing error. We surmise that the shell activity is now at a stable phase for a few years.     

The system of DO cassiopeiae: Photoelectric observations and light curves analysis

The newB andV photoelectric observations of DO Cas, obtained during 1979 and 1980, are presented, analysed, and discussed. The observations were made at the National Observatory of Athens, Greece, and their analysis was based on the frequency domain, techniques. New geometric, photometric, and absolute elements for the system are given.     

Photoelectric observations of SZ lyncis and its period variation

Between 1980 December and 1984 March, we made photoelectric observations of SZ Lyn on 15 nights and recorded 19 times of maxima. Combining with those published, we now have a total of 139 times of maxima. Applying a second-order least squares reduction to this data, we found that the period of SZ Syn is definitely increasing at a rate of 0.165 seconds per 100 years or (6.32 ± 0.62) × 10⁻¹² d/period.     

Photoelectric observations of VW Cephei in R and I

Photoelectric observations of VW Cephei in R and I bands were made from 1989 to 1992. 17 primary minima and 11 secondary minima were covered, it is found from the present observations that the period abruptly changed aboutl990 and the maxima I and II exchanged between 1992 and 1993.(Communicated by M. Kitamura)     

Photoelectric observations of AX Virginis and a photometric solution

We obtained a photoelectric light curve (686 points) of AX Vir in yellow light and one principal minimum time and two secondary minimum times. A photometric orbit (the first one published, to our knowledge) is derived using the Russell-Merrill model.     

Photoelectric observations of the occultation of 136 tauri by Venus

The occultation of 136 Tau on May 11, 1988 was observed at the Observatorium Hoher List. The ingress was recorded photoelectrically by the dual beam photometer while the egress was observed visually. A bona fide curve fitting reduction yielded a scale height differing from earlier p.e. occultation results and is in better agreement with theoretical expectations.     

Photoelectric observations of CPM stars in theBVRI system

Summary A photometric program to estimate the frequency of close unresolved companions in visual binary systems has been developed. The sensitivity of the detection depends on the accuracy of the differential photometric measurements of binary components. Unresolved companions up to seven magnitudes fainter than the primary are detectable in theBVRI photometric system. Presented by K. D. Rakos.     

Photoelectric UBV observations and period study of AK Herculis system

New photoelectric UBV observations of the W Ursae Majoris-type eclipsing binary AK Her are presented. The system exhibits many phenomena such as O'Connell effect, unequal depth, phase shift and different duration in secondary eclipse due to its totality, which have been studied. O'Connell effect-duration relation may be exist. The (O-C) curve has been obtained and the new light elements have been calculated. The analysis of the minima-times data of the system reveals possible sinusoidal orbital period variation (LITE). The study of the (O-C)curve, the light curves, O'Connell effect and the duration effect have led to that the system is likely a case which undergoes cyclic around the marginal contact state conservatively with mass transfers between its components, i.e.in TRO mode. This revised version was published online in July 2006 with corrections to the Cover Date.     

Photoelectric observations in a wide-field area around the Praesepe cluster

The PPM catalogue numbers, photoelectric magnitudes V, color-indexes U – B, B – V, V – R and rms errors of their determinations for 51 stars of the secondary wide-angle photoelectric standard are published. The catalogue accuracy of quantities mentioned above is 0.007, 0.015, 0.006, 0.006 mag, respectively. A list of ten stars which are probably variable is published.     

W UMa-type stars BV Dra conis and BW DRa conis: Photoelectric observations

Photoelectric UBV observations of two W UMa-type stars, BV Dra (ADS 9537A) and BW Dra (ADS 9537B), are presented. New periods and epochs of minima are given for both variables, and magnitudes at maximum light are determined from standard star observations. It is concluded that these variables are quite normal W UMa stars.The two variables are members of the visual binary star ADS 9537, for which the angular separation and the position angle are determined from the photographic observations.On leave of absence from Dept. of Earth Science and Astronomy, College of General Education University of Tokyo.     

Photoelectric observations of the flare star BD + 55° 1823

A light variation in Johnson'sV-band of flare star EV Lac has been registered by Pettersen (1980). The cycle length was 4 _. ^d 378 with amplitude about 0 _. ^m 07. A Fourier analysis programme has been applied on our measured data of the flare star BD+55°1823 in Johnson'sV andB bands. A period of 16^d and amplitude of 0 _. ^m 14 have been detected in theV-band.     

Photoelectric observations of long-period RS CVn binary CQ aurigae

Long-period RS CVn-type binary CQ Aur was observed in 1987 and 1988.B andV light curves for the 1987 and 1988 epochs have been analyzed for the photometric solution by the modified Wilson and Devinney computing code with adjustable spot parameters. One-spot fit is good enough for the 1987 epoch while a wider distribution of spots in longitude is required for the 1988 epoch. The spot covers approximately 3% of total surface area of the cooler component. Absolute dimensions were deduced by combining Popper's spectroscopic results. The volume of the cooler component is approximately 100 times larger than that of the hotter component. Both components are subgiants but the cooler component evolved more than the hotter component.