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 which the spin period of the white dwarf and the binary orbital period differ by --1 per cent. As such these `BY Cam' stars are important objects with which to probe the field structure of the magnetic white dwarf and ultimately the nature of synchronization of AM Her binaries. We confirm asynchronous rotation of the magnetic white dwarf with respect to the binary. We find evidence that the accretion stream accretes directly on to the white dwarf as in AM Her systems, but further, the stream impacts on to different magnetic poles over the course of the beat period. We present evidence that the optical and hard X-ray light curves modulate in phase, but together they are out of phase with the soft X-ray light curve. We confirm the spin down of the white dwarf which is expected to lead to the synchronization of the spin and orbital periods of BY Cam.

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Кафедра астрономии и Астрономическая обсерватория Одесского национального университета Описан алгоритм средневзвешенной звезды сравнения при фотометрии с использованием ПЗС-камер. Приведены формулы самосогласованного определения весов и среднеквадратичного разброса звезд сравнения и средневзвешенной звезды. Данный алгоритм использования искуственной звезды сравнения, вместо одной контрольной звезды позволяет улучшить точность определения звезды сравнения до десятков процентов и иногда раз. Описана компьютерная программа Multi-Column View (MCV), которая дополнительно позволяет проводить визуализацию, удаление или интерполяцию данных перед использованием алгоритма средневзвешенной звезды сравнения. АЛГОРИТМ ШТУЧНОЇ ЗОРI ПОРIВНЯННЯ ДЛЯ ПЗС ФОТОМЕТРIЇ, Андронов I.Л., Бакланов О.В. Описано алгоритм середньозваженої зорi порiвняння при фотометрии з використанням ПЗС-камер. Приведенi формули самоузгодженого визначення ваги та середньоквадратичного розсiяння зорь порiвняння i середньозваженої зорi. Цей алгоритм використання штучної зорi порiвняння замiсть однiєї контрольної зорi дозволяє покращити точнiсть визначення зорi порiвняння до десяткiв вiдсоткiв и iнодi разiв. Описана комп'ютерна программа Multi-Column View (MCV), що додатково дозволяє проводити вiзуалiзацiю, вилучення або iнтерполяцiю даних перед використанням алгоритму середньозваженої зорi порiвняння.

Abstract.We report the discovery of a bright X-ray transient object, XMMU J174554.4-285456, observed in outburst with XMM-Newton on October 3, 2002, and located at 6.3 from Sgr A*, the supermassive black hole at the Galactic center. This object exhibits a very large X-ray luminosity variability of a factor of about 1300 between two X-ray observations separated by four months. The X-ray spectrum is best fitted by a power-law with a photon index of 1.6±0.2 and absorption column density of 14.1 +1.6 −1.4 × 10 22 cm −2 . This large absorption suggests this source is located at the distance of the Galactic center, i.e., 8 kpc. The 2-10 keV luminosity is about 1.0 × 10 35 (d/8 kpc) 2 erg s −1 . A pulsation period of about 172 s is hinted by the timing analysis. The X-ray properties strongly suggest a binary system with either a black hole or a neutron star for the compact object.

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Abstract. Analytic expressions in a general form are derived for the expectation of functions related to the smoothing the astronomical signals using local approximations with additional weights. No restrictions are made on distribution of the times of the signal. Applications are made for polynomial fits of orders 0 and 2 and weights p(z) = 1 and (1−z 2 ) 2 . These variable weights ensure that the smoothing function will be both continuous and differentiable, which is important for determining the extrema and the shape of the variations. Special attention is paid to evenly spaced time series data, which if their number is large enough will allow one to obtain analytic expressions for the main functions.

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−25 E 4 . Thus the rate of the spin-up of the white dwarf is decreasing. An alternative explanation is that the spin-up has been stopped during recent years. The deviations between the amplitudes of the spin variability in V and R, as well as between phases are not statistically significant. However, the orbital light curves exhibit distinct difference; the corresponding color index shows a nearly sinusoidal shape with a maximum at orbital phase ∼0.2. The variations of the amplitude of spin waves shows a short maximum at the phase of the orbital dip. The corrected ephemeris for orbital minima is Min.HJD = 2 448 368.7225(12) + 0.d 13474841(6) · (E − 24849) with a narrow dip occuring 0.07P later. The rate of the spin period variation seems to be changed, justifying the necessity of regular observations of intermediate polars.