An analysis of X-ray and optical light curves of the magnetic cataclysmic variable (MCV) BY Cam is presented. This system is one of three MCVs in whi

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics

BY Camelopardalis is one of only three known asynchronous AM Herculis-type cataclysmic variables (CVs). The slightly different spin and orbital periods lead to a predicted beat period of about two weeks. We collected at least one orbit worth of observations of BY Cam on each of 46 nights over a period of four months to detect and study the beat phenomena. We detected a period of 7.26 d both in the O—C values of the photometric variation and in the amplitude of a sine wave fit to individual orbits of data. This period most likely represents half of the true beat period of 14.52 d. We also measured a photometric period of 0.137111 d, shorter than the previously suggested spin periods, from our large data set. Smaller sections of data showed a period closer to the previously published spin period. The photometric variation is caused by the white dwarf spin, but the accretion spot slips on the white dwarf surface over the course of a beat period, causing the shorter photometric period. Given the observed beat and photometric periods, we obtain a white dwarf spin period of 0.1384339 ± 0.000003 d, consistent with previous measurements. A search of a subset of the data for periodicities from 6 to 40 min showed significant power in this range consistent with shot noise, flickering and broad peaks around 10 and 15 min.

This paper reviews the most important components of the national project of the Ukrainian Virtual Observatory (UkrVO). Among them, there is the establishment of a Joint Digital Archive (JDA) of...

The algorithm of the “mean weighted” comparison star for the photometry using CCD-cameras, has been described. The expressions for self-consistent determination of the weights and scatter of the comparison stars and the “mean weighted” star have been presented. This algorithm of using the “artificial” star instead of one control star allows to improve accuracy of the comparison star determination by dozens of percent or sometimes by few times. The computer program “Multi-Column View” (MCV) has been described, which allows to visualize, delete or interpolate the data before applying the algorithm of the “mean weighted” comparison star.

The aim of this paper is to introduce the software and astronomical web-services developed in frame of the Ukraine Virtual Observatory (UkrVO) and VIrtual Roentgen and Gamma Observatory (VIRGO) to the broad astronomical community. We report briefly on such web-services as the public databases “Sky Maps” of X-ray observations by XMM-Newton, the Earth Orbital Parameters for International Earth Rotation System, and the UkrVO Joint Digitized Archive of astroplates. We refer to such software as the “Multi-Column View”, “Variable Stars Calculator”, “FrameSmooth” for variable star’s research and “Collection Light Technology” (CoLiTec) software for search and discovery of new Solar System bodies.