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We analyze spectroscopic and photometric observations of the eclipsing polar BS Tri. The polar's light curve shape variations can be interpreted by changing contributions of the accretion stream to the integral radiation of the system. Based on the radial velocity curves of the irradiated part of the secondary, we refine the masses of the system components, $M_1 = 0.60 \pm 0.04 M_{\odot}$, $M_2 \approx 0.12 M_{\odot}$, and the orbital inclination, $i=85\pm 0.5^{\circ}$. The polar's spectra reveal cyclotron harmonics forming in an accretion spot with a magnetic field strength of $B=22.7 \pm 0.4$ MG and an average temperature of $T \sim 10$ keV. In addition to the cyclotron harmonics, the BS Tri spectra contain Zeeman components of H$\alpha$ line, which are probably formed in the cool halo near the accretion spot. The orientation of the magnetic dipole and the coordinates of the accretion spot are estimated by modeling the light curves of the polar. We show that for a satisfactory description of the BS~Tri light curves we have to take into account the variability of the spot's optical depth along the line of sight. Doppler maps of BS Tri show a part of the accretion stream with a trajectory close to ballistic near the Lagrange point L$_1$, and another part of the stream moving along the magnetic field lines. The estimate of the stagnation region position found from the Doppler tomograms is consistent with the photometric estimates of the accretion spot position.

Optical, J, and K photometric observations of the KV UMa black hole X-ray nova in its quiescent state obtained in 2017-2018 are presented. A significant flickering within light curves was not detected, although the average brightness of the system faded by $\approx 0.1^m$ during 350 days. Changes in the average brightness were not accompanied with the increase or the decrease of the flickering. From the modelling of five light curves the inclination of the KV UMa orbit and the black hole mass were obtained: $i=74^{\circ}\pm 4^{\circ}$, $M_{BH}=(7.06\div 7.24)M_{\odot}$ dependently on the used mass ratio. The non-stellar component of the spectrum in the range $\lambda=6400\div 22000$\r{A} can be fitted by a power law $F_{\lambda}\sim \lambda^{\alpha}$, $\alpha\approx -1.8$. The accretion disk orientation angle changed from one epoch to another. The model with spots on the star was inadequate. Evolutionary calculations using the "Scenario Machine" code were performed for low mass X-ray binaries, a recently discovered anomalously rapid decrease of the orbital period was taken into account. We showed that the observed decrease can be consistent with the magnetic stellar wind of the optical companion which magnetic field was increased during the common envelope stage. Several constraints on evolutionary scenario parameters were done., Comment: 24 pages, 16 figures, accepted by MNRAS

The transient event labeled as TCP J05074264+2447555 recently discovered towards the Taurus region was quickly recognized to be an ongoing microlensing event on a source located at distance of only $700-800$ pc from Earth. Here, we show that observations with high sampling rate close to the time of maximum magnification revealed features that imply the presence of a binary lens system with very low mass ratio components. We present a complete description of the binary lens system which hosts an Earth-like planet with most likely mass of $9.2\pm 6.6$ M$_{\oplus}$. Furthermore, the source estimated location and detailed Monte Carlo simulations allowed us to classify the event as due to the closest lens system, being at a distance of $\simeq 380$ pc and mass $\simeq 0.25$ M$_{\odot}$., Comment: Accepted for publication on MNRAS, 2018. 6 Pages, 5 Figures. References updated

Photometric observations of the low-mass X-ray binary system A0620-00=V616 Mon are performed in the optical (unfiltered light, lambda_eff~6400A) and the near-infrared J and K-bands. The mean system flux, the orbital light curve shape and the flickering amplitude dependences on wavelength are examined for two activity stages of the system remaining in quiescence. In 2015-16 A0620-00 was in passive stage (as by Cantrell et al., 2008) exhibiting the regular orbital light curves and low flickering. In less than 230 days in 2016-17 the system switched into active stage: the brightness increased by ~0.2-0.3 mag, the orbital light curve changed while the flickering amplitude increased more than twice. The object regular orbital light curves were fitted by models with "cold" spots on the optical star surface and without those. These models reproduce the observed orbital light curves both in passive and in active stages. The dependence of the mean square flickering amplitude (in fluxes, extinction corrected) on wavelength is computed in the lambda 6400-22000AA range. In active stage, the observed flickering amplitude decreases over the whole studied range and may be represented as Delta F_fl~lambda^{-2} which corresponds to the free-free emission of optically thin high-temperature plasma. In passive stage, flickering obeys Delta F_fl~lambda^{-4} law in the range 6400-12500AA that corresponds to the thermal radiation of optically thick high-temperature plasma. At longer wavelengths the flickering amplitude dependence is flat which may imply existence of a synchrotron component of the relativistic jets emission. These flickering features let us propose that the flickering mechanism includes at least two components: thermal and, apparently, synchrotron, that agrees with the recent discovery of the variable linear polarization of the IR system emission (Russell et al., 2016)., Comment: Submitted to MNRAS. Comments are welcome

V616 Mon = A0620-00 is a prototype of black hole transient X-ray binaries. Our 2003-16 optical photometry of the object during X-ray quiescence, obtained by 50-250 cm telescopes in Crimea, Caucasus Mountains and Slovakia, consists of ~ 7660 CCD frames in Johnson-Cousins $V,R,R_C,I$ bands and the integral light. During 2003, 2008-9 and 2015-16 passive states, the phase light curve of the binary exhibited mainly variations caused by an ellipsoidal shape of the red dwarf component. During 2004-6 and 2009-14 active states a significant aperiodic broad-band variability (flickering) was present, arising in a black hole accretion disk and a bright spot, where the mass transfer stream hits the outer edge of the disk. Long term photometry of our minima times, together with available positions of superior conjunctions of the red dwarf found from spectroscopy, allowed us to refine the orbital period of V616 Mon to 0.32301407(5) days.

We present UBVRI photometry of the supernova 2011fe in M101, obtained in the interval of 1-652 days after its discovery, as well as one spectrum, taken 105 days after the brightness maximum in the B band. We derived parameters of the light curves, constructed the colour curves and a "quasi-bolometric" light curve. The light curves, colour evolution and spectrum of the object indicate that SN 2011fe belongs to the "normal" subset of type Ia supernovae. It is practically identical to a well-studied "normal" SN Ia 2003du., Comment: 16 pages, 6 figures

SDSS J080434.20+510349.2 is the 13th dwarf nova containing a pulsating white dwarf. Among the accreting pulsators that have experienced a dwarf novae outburst, SDSS J0804 has the most dramatic history of events within a short time scale: the 2006 outburst with 11 rebrightenings, series of December 2006 - January 2007 mini-outbursts, the 2010 outburst with 6 rebrightenings. Over 2006-2011, SDSS J080434.20+510349.2 in addition to positive 0.060^d superhumps during the outburst and 1-month post-outburst stage, 0.059005^d orbital humps in quiescence, displayed a significant short-term variations with periods P1 = 12.6 min, P2 = 21.7 min, P3 = 14.1 min and P4 = 4.28 min. The 12.6-min periodicity first appeared 7 months after the 2006 outburst and was the most prominent one during the following \sim 900 days. It was identified as non-radial pulsations of the white dwarf. The period of this pulsations varied within a range of 36 s, and amplitude changed from 0.013m to 0.03m. Simultaneously one could observe the 21.7-min and 14.3-min periodicities with a much lower significance level. During the minioutbursts the 21.7-min periodicity became the most powerful, the 12.6-min periodicity was less powerful, and the 12.6-min periodicity had the lowest significance. After the 2011 outburst the most prominent short-term periodicity appeared \sim 7 months after the outburst, but at 4.28 min. We identified that variability with periods P2, P3 and P4 could be additional pulsation modes, however the relation of P4 to white dwarf pulsation also can't be excluded., Comment: 5 pages, 7 figures

We present the results of photometric observations of SDSS J080434.20+510349.2 in its low state and during an outburst and spectroscopy during the outburst. We found such peculiarities as a long-term outburst with amplitude probably not less than 6m, rarity of the outbursts, eleven rebrightenings, and a short (0.059713(7) d) superhump period. We conclude that this star belongs to the WZ Sge-type subclass of cataclysmic variables. The spectrum shows both emission and absorption lines of H and He superimposed on the blue continuum. We also found 8 -- 9 min. brightness variations during the end of the super-outburst plateau that could be related to pulsations of the white dwarf in the binary., Comment: Published in 15th European Workshop on White Dwarfs ASP Conference Series, Vol. 372, proceedings of the conference held 7-11 August, 2006 in Leicester, United Kingdom. Edited by Ralf Napiwotzki and Matthew R. Burleigh. San Francisco: Astronomical Society of the Pacific, 2007., p.511

Several SU UMa-type dwarf novae, in particular, WZ Sge-type stars tend to exhibit rebrightenings after superoutbursts. The rebrightening phenomenon is problematic for the disk instability theory of dwarf novae since it requires a large amount of remnant matter in the disk even after superoutbursts. Here, we report our optical and infrared observations during the first-ever outburst of a new dwarf nova, SDSS J102146.44+234926.3. During the outburst, we detected superhumps with a period of 0.056281 +/- 0.000015 d, which is typical for superhump periods in WZ Sge stars. In conjunction with the appearance of a long-lived rebrightening, we conclude that the object is a new member of WZ Sge stars. Our observations, furthermore, revealed infrared behaviors for the first time in the rebrightening phase of WZ Sge stars. We discovered prominent infrared superhumps. We calculate the color temperature of the infrared superhump source to be 4600-6400 K. These temperatures are too low to be explained with a fully-ionized disk appearing during dwarf nova outbursts. We also found a Ks-band excess over the hot disk component. These unprecedented infrared activities provide evidence for the presence of mass reservoir at the outermost part of the accretion disk. We propose that a moderately high mass-accretion rate at this infrared active region leads to the long-lived rebrightening observed in SDSS J102146.44+234926.3., Comment: 11 pages, 10 figures. Accepted for publication in PASJ