We present a new observational campaign, Dwarf, aimed at detection of circumbinary extrasolar planets using the timing of the minima of low-mass eclipsing binaries. The observations will be performed within an extensive network of relatively small to medium-size telescopes with apertures of similar to 20-200 cm. The starting sample of the objects to be monitored contains (i) low-mass eclipsing binaries with M and K components, (ii) short-period binaries with a sdB or sdO component, and (iii) post-common-envelope systems containing a WD, which enable to determine minima with high precision. Since the amplitude of the timing signal increases with the orbital period of an invisible third component, the timescale of the project is long, at least 5-10 years. The paper gives simple formulas to estimate the suitability of individual eclipsing binaries for the circumbinary planet detection. Intrinsic variability of the binaries (photospheric spots, flares, pulsation etc.) limiting the accuracy of the minima timing is also discussed. The manuscript also describes the best observing strategy and methods to detect cyclic timing variability in the minima times indicating the presence of circumbinary planets. First test observations of the selected targets are presented ((c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Tightest known quadruple system VW LMi consists of contact eclipsing binary with P-12 = 0.477 551 d and detached binary with P-34 = 7.930 63 d revolving in rather tight, 355.0-d orbit. This paper presents new photometric and spectroscopic observations yielding 69 times of minima and 36 disentangled radial velocities for the component stars. All available radial velocities and minima times are combined to better characterize the orbits and to derive absolute parameters of components. The total mass of the quadruple system was estimated at 4.56 M-circle dot. The detached, non-eclipsing binary with orbital period P = 7.93 d is found to show apsidal motion with U approximate to 80 yr. Precession period in this binary, caused by the gravitational perturbation of the contact binary, is estimated to be about 120 yr. The wide mutual orbit and orbit of the non-eclipsing pair are found to be close to coplanarity, preventing any changes of the inclination angle of the non-eclipsing orbit and excluding occurrence of the second system of eclipses in future. Possibilities of astrometric solution and direct resolving of the wide, mutual orbit are discussed. Nearby star, HD 95606, was found to form loose binary with quadruple system VW LMi.

We give an introduction information about the KOROAPS (KOsice ROztoky Automatic Photometry System). It is a system for a large scale automatic multicolor monitoring and variable stars searching. It is in a development at Safarik University in Kosice in cooperation with Roztoky Observatory. The system is now in a test operation at Roztoky Observatory. System consists of Nikkor photolense 2/200 equipped with SBIG ST8 CCD camera and set of the standard VRI photometric filters. It is placed on Celestron’s CG-5 Advanced mount. We give description of the basic properties of the instrument, data reduction pipeline and operational modes of the instrument.

New photoelectric and CCD observations of the eclipsing contact binary systems V344 Lac and V1191 Cyg are presented and analyzed. All available times of minimum light were used to study period changes of the systems and determine up-to-date ephemerides. The orbital period of V1191 Cyg is found to be increasing at a very fast rate. The photometric elements were determined using the new light curve, radial-velocity curve and broadening function fitting code ROCHE.

We present spectral energy distribution (SED) in the 0.12-5.0 mu continuum of BF Cyg and AG Dra during their active phases. Fitting observations by a three-component model of radiation of symbiotic binaries, we show and discuss main differences in their SEDs. We determined physical parameters of their components of radiation.