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RY Sct is a unique massive binary star system in a short transitional evolutionary phase. It is an eclipsing binary where both stars have overfilled their Roche cavities, so that the system is in an “overcontact” state. It is surrounded by a young circumstellar nebula. The binary is regarded as a rare progenitor of a type WR+OB system. RY Sct is close to the Eddington luminosity limit, so that radiative pressure plays an important role in mass loss. At least one of the components of the close binary may be associated with a rare class of LBV stars or the so-called S Doradus variables. We have calculated the orbital elements using the old photometric data of Zakirov and Kumsiashvili and new spectral data, together with an analysis of HST observations. A model was examined according to which the components of RY Sct are in an overcontact state and fill their Roche cavities. The brighter primary component transfers mass to the more massive but less bright secondary. The binary system is surrounded by a common envelope. As initial parameters we, chose a mass ratio q = 4.42 and orbital period P = 11d.12471, and used an orbital inclination of i = 75.6°.

Full list of authors: Aivazyan, V; Almualla, M.; Antier, S.; Baransky, A.; Barynova, K.; Basa, S.; Bayard, F.; Beradze, S.; Berezin, D.; Blazek, M.; Boutigny, D.; Boust, D.; Broens, E.; Burkhonov, O.; Cailleau, A.; Christensen, N.; Cejudo, D.; Coleiro, A.; Coughlin, M. W.; Datashvili, D.; Dietrich, T.; Dolon, F.; Ducoin, J-G; Duverne, P-A; Marchal-Duval, G.; Galdies, C.; Granier, L.; Godunova, V; Gokuldass, P.; Eggenstein, H. B.; Freeberg, M.; Hello, P.; Inasaridze, R.; Ishida, E. E. O.; Jaquiery, P.; Kann, D. A.; Kapanadze, G.; Karpov, S.; Kiendrebeogo, R. W.; Klotz, A.; Kneip, R.; Kochiashvili, N.; Kou, W.; Kugel, F.; Lachaud, C.; Leonini, S.; Leroy, A.; Leroy, N.; Su, A. Le Van; Marchais, D.; Midavaine, T.; Moeller, A.; Morris, D.; Natsvlishvili, R.; Navarete, F.; Noysena, K.; Nissanke, S.; Noonan, K.; Orange, N. B.; Peloton, J.; Popowicz, A.; Pradier, T.; Prouza, M.; Raaijmakers, G.; Rajabov, Y.; Richmond, M.; Romanyuk, Ya; Rousselot, L.; Sadibekova, T.; Serrau, M.; Sokoliuk, O.; Song, X.; Simon, A.; Stachie, C.; Taylor, A.; Tillayev, Y.; Turpin, D.; Vardosanidze, M.; Vlieghe, J.; Tosta e Melo, I; Wang, X. F.; Zhu, J., We present our follow-up observations with GRANDMA of transient sources revealed by the Zwicky Transient Facility (ZTF). Over a period of six months, all ZTF alerts were examined in real time by a dedicated science module implemented in the Fink broker, which will be used in filtering of transients discovered by the Vera C. Rubin Observatory. In this article, we present three selection methods to identify kilonova candidates. Out of more than 35 million alerts, a hundred sources have passed our selection criteria. Six were then followed-up by GRANDMA (by both professional and amateur astronomers). The majority were finally classified either as asteroids or as supernovae events. We mobilized 37 telescopes, bringing together a large sample of images, taken under various conditions and quality. To complement the orphan kilonova candidates, we included three additional supernovae alerts to conduct further observations during summer 2021. We demonstrate the importance of the amateur astronomer community that contributed images for scientific analyses of new sources discovered in a magnitude range r′ = 17 − 19 mag. We based our rapid kilonova classification on the decay rate of the optical source that should exceed 0.3 mag d−1. GRANDMA’s follow-up determined the fading rate within 1.5 ± 1.2 d post-discovery, without waiting for further observations from ZTF. No confirmed kilonovae were discovered during our observing campaign. This work will be continued in the coming months in the view of preparing for kilonova searches in the next gravitational-wave observing run O4. © 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society., SA and CL acknowledge the financial support of the Programme National Hautes Energies (PNHE). SA acknowledges the financial support of CNES. SA is grateful for financial support from the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) through the VIDI (PI: Nissanke). SA dedicates her contribution to Rayan Ouram, who is a source of inspiration for bravity and humanity for GRANDMA. DT acknowledges the financial support of CNES post-doctoral program. UBAI acknowledges support from the Ministry of Innovative Development through projects FA-Atech-2018-392 and VA-FA-F-2-010. RI acknowledges Shota Rustaveli National Science Foundation (SRNSF) grant No - RF/18-1193. TAROT. has been built with the support of the Institut National des Sciences de l’Univers, CNRS, France. MP, SK, and MM are supported by European Structural and Investment Fund and the Czech Ministry of Education, Youth and Sports (Projects CZ.02.1.01/0.0/0.0/16_013/0001403, CZ.02.1.01/0.0/0.0/18_046/0016007 and CZ.02.1.01/0.0/0.0/15_003/0000437). The FRAM telescope is also supported by the Czech Ministry of Education, Youth and Sports (projects LM2015046, LM2018105, LTT17006). NBO and DM acknowledge financial support from NASA MUREP MIRO award 80NSSC21M0001, NASA EPSCoR award 80NSSC19M0060, and NSF EiR award 1901296. PG acknowledges financial support from NSF EiR award 1901296. DAK acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot) XW is supported by the National Science Foundation of China (NSFC grants 12033003 and 11633002), the Scholar Program of Beijing Academy of Science and Technology (DZ:BS202002), and the Tencent Xplorer Prize. The work of FN is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The GRANDMA consortium thank the amateur participants to the kilonova-catcher program. The kilonova-catcher program is supported by the IdEx Université de Paris, ANR-18-IDEX-0001. This research made use of the cross-match service provided by CDS, Strasbourg. MC acknowledges support from the National Science Foundation with grant numbers PHY-2010970 and OAC-2117997. GR acknowledges financial support from the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) through the Projectruimte and VIDI grants (PI: Nissanke). Thanks to the National Astronomical Research Institute of Thailand (Public Organization), based on observations made with the Thai Robotic Telescope under program ID TRTC08D_005 and TRTC09A_002. S., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

We present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA). The network consists of 21 telescopes with both photometric and spectroscopic facilities. They are connected together thanks to a dedicated infrastructure. The network aims at coordinating the observations of large sky position estimates of transient events to enhance their follow-up and reduce the delay between the initial detection and optical confirmation. The GRANDMA programme mainly focuses on follow-up of gravitational-wave alerts to find and characterize the electromagnetic counterpart during the third observational campaign of the Advanced LIGO and Advanced Virgo detectors. But it allows for follow-up of any transient alerts involving neutrinos or gamma-ray bursts, even those with poor spatial localization. We present the different facilities, tools, and methods we developed for this network and show its efficiency using observations of LIGO/Virgo S190425z, a binary neutron star merger candidate.We furthermore report on allGRANDMAfollow-up observations performed during the first six months of the LIGO-Virgo observational campaign, and we derive constraints on the kilonova properties assuming that the events' locations were imaged by our telescopes. © 2019 The Author(s)., Parts of this research were conducted by the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), through project number CE170100004. EJH acknowledges support from a Australian Research Council DECRA Fellowship (DE170100891). AdUP and CCT acknowledge support from Ramon y Cajal fellowships RyC-2012-09975 and RyC-201209984 and the Spanish Ministry of Economy and Competitiveness through project AYA2017-89384-P. DAK acknowledges support from the Spanish research projectAYA2017-89384-P. MBacknowledges funding as `personal tecnico de apoyo' under fellowship number PTA2016-13192-I. MC is supported by the David and Ellen Lee Postdoctoral Fellowship at the California Institute of Technology. SA is supported by the CNES Postdoctoral Fellowship at Laboratoire AstroParticule et Cosmologie. SA, AC, CL, and RM acknowledge the financial support of the UnivEarthS Labex program at Sorbonne Paris Cite (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). SA and NL acknowledge the financial support of the Programme National Hautes Energies (PNHE). DT acknowledges the financial support of the Chinese Academy of Sciences (CAS) PIFI post-doctoral fellowship program (program C). UBAI acknowledges support from the Ministry of Innovative Development through projects FA-Atech-2018-392 and VA-FAF-2-010. IRiS has been carried out thanks to the support of the OCEVU Labex (ANR-11-LABX-0060) and the A*MIDEX project (ANR-11-IDEX-0001-02) funded by the 'Investissements d'Avenir' French government program. IRiS and T120 thank all the Observatoire de Haute-Provence staff for the permanent support. SB, NK, RN, and MV acknowledge the Shota Rustaveli National Science Foundation (SRNSF grant No 218070). TAROT has been built with the support of the Institut National des Sciences de l'Univers, CNRS,France. TAROT is funded by theCNESand thanks the help of the technical staff of the Observatoire de Haute Provence, OSU-Pytheas.

According to earlier investigations by Turner and co-authors, P Cygni could be a member of a hypothetical, sparsely populated open cluster. The star lies near the east boundary of this hypothetical cluster. There is another known open cluster, IC 4996, in the vicinity of P Cygni. The same authors believe that the above mentioned two clusters are connected to each other and they could represent a double cluster. As P Cygni is a hypergiant and consequently has very strong and variable stellar wind, so a cluster membership can enable us to determine the age, distance, and reddening of the star relatively precisely. We used new data of different catalogues, for example, PPMXL and Gaia and tried to resolve the problem.

We use observations of the Luminous Blue Variable (LBV) P Cygni spanning seven decades, along with signal processing methods, to identify a periodicity in the stellar luminosity. We find a distinct period of $4.7 \pm 0.3$ years together with shorter periods. The periodicity is a possible indication of a binary companion passing in an eclipse-like event from the dense LBV wind, and if so it is the first observational indication that P Cygni is a binary system. This may support models that contribute giant LBV eruptions to interaction with a binary companion. We discuss other interpretations for the periodicity as well., Accepted to New Astronomy

Until recent decades, it was considered that all Luminous Blue Variables are single massive and high luminosity stars. Now for several of them a companion has been found. The opinion exists that P Cygni also has a companion with an orbital period of about seven years. In accordance with this hypothesis, a known powerful eruption occurred near the periastron point. P Cygni, as well as several other well-known Luminous Blue Variable (LBV) stars, is a so-called "Supernova Impostor" because it survived after a powerful outburst. However, there were cases during the last decade when a LBV star survived after a powerful giant eruption, and then after a few years, explode as a supernova. Because the real reason for the great eruption and characteristic light variability of LBV, including P Cygni, is not established yet, any kind of photometric and spectral observational data is very significant. We present the results of analysis of the long-term photometric observations of hypergiant P Cygni. On the basis of these data, different quasi-periodic brightness changes of the star were revealed.

Methods of neutralisation of different types of soils contaminated with heavy metals are studied. Certain strains of microorganisms have been selected, local microflora has been studied and identified at the genus level in laboratory conditions. Considering the conducted works, development of modified forms of humic acids, stimulation of local microorganisms and creation of geochemical barriers using local natural raw materials is recomended. Obtained results makes possible to develop comprehensive and rational model by means of inovative technologies for effective purification of soils contaminated with heavy metals.

Luminous Blue Variables (LBV) are extremely rare and enigmatic stars on the short-lived evolutionary phase with different variation scales of brightness and spectrum. Some of them are confirmed binary systems and even secondary components have found by direct imaging. The blue supergiant P Cygni is one of the prototypes of Luminous Blue Variables, showing photometric and spectroscopic variability on various timescales. We are going to present results of the old and new photometric observations of P Cygni. Old 1951-1983 years photometric observations were made by E. Kharadze and N. Magalashvili in the Abastumani Astrophysical Observatory, Georgia, which we found, recalculated and made conclusion that the star should undergo the next great eruption in some 100 years. New observations were obtained in 2014, using the 48 cm Cassegrain telescope of the Abastumani Observatory. Some interesting behaviors of the light curves were revealed.

Full list of authors: Antier, S.; Agayeva, S.; Almualla, M.; Awiphan, S.; Baransky, A.; Barynova, K.; Beradze, S.; Blažek, M.; Boër, M.; Burkhonov, O.; Christensen, N.; Coleiro, A.; Corre, D.; Coughlin, M. W.; Crisp, H.; Dietrich, T.; Ducoin, J. -G.; Duverne, P. -A.; Marchal-Duval, G.; Gendre, B.; Gokuldass, P.; Eggenstein, H. B.; Eymar, L.; Hello, P.; Howell, E. J.; Ismailov, N.; Kann, D. A.; Karpov, S.; Klotz, A.; Kochiashvili, N.; Lachaud, C.; Leroy, N.; Lin, W. L.; Li, W. X.; Mašek, M.; Mo, J.; Menard, R.; Morris, D.; Noysena, K.; Orange, N. B.; Prouza, M.; Rattanamala, R.; Sadibekova, T.; Saint-Gelais, D.; Serrau, M.; Simon, A.; Stachie, C.; Thöne, C. C.; Tillayev, Y.; Turpin, D.; de Ugarte Postigo, A.; Vasylenko, V.; Vidadi, Z.; Was, M.; Wang, X. F.; Zhang, J. J.; Zhang, T. M.; Zhang, X. H., GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger Addicts) is a network of 25 telescopes of different sizes, including both photometric and spectroscopic facilities. The network aims to coordinate follow-up observations of gravitational-wave (GW) candidate alerts, especially those with large localization uncertainties, to reduce the delay between the initial detection and the optical confirmation. In this paper, we detail GRANDMA's observational performance during Advanced LIGO/Advanced Virgo Observing Run 3 (O3), focusing on the second part of O3; this includes summary statistics pertaining to coverage and possible astrophysical origin of the candidates. To do so, we quantify our observation efficiency in terms of delay between GW candidate trigger time, observations, and the total coverage. Using an optimized and robust coordination system, GRANDMA followed-up about 90 per cent of the GW candidate alerts, that is 49 out of 56 candidates. This led to coverage of over 9000 deg2 during O3. The delay between the GW candidate trigger and the first observation was below 1.5 h for 50 per cent of the alerts. We did not detect any electromagnetic counterparts to the GW candidates during O3, likely due to the very large localization areas (on average thousands of degrees squares) and relatively large distance of the candidates (above 200 Mpc for 60 per cent of binary neutron star, BNS candidates). We derive constraints on potential kilonova properties for two potential BNS coalescences (GW190425 and S200213t), assuming that the events' locations were imaged. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society., Parts of this research were conducted by the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), through project number CE170100004. EJH acknowledges support from an Australian Research Council DECRA Fellowship (DE170100891). AdUP and CCT acknowledge support from Ramon y Cajal fellowships RyC-2012-09975 and RyC-2012-09984 and the Spanish Ministry of Economy and Competitiveness through project AYA2017-89384-P. DAK acknowledges Spanish research project RTI2018-098104-J-I00 (GRBPhot). MB acknowledges funding as 'personal tecnico de apoyo' under fellowship number PTA2016-13192-I. SA is supported by the CNES Postdoctoral Fellowship at Laboratoire AstroParticule et Cosmologie. SA and CL acknowledge the financial support of the Programme National Hautes Energies (PNHE). DT acknowledges the financial support of CNES postdoctoral program. UBAI acknowledges support from the Ministry of Innovative Development through projects FA-Atech-2018-392 and VA-FA-F-2-010. SB acknowledges Shota Rustaveli National Science Foundation (SRNSF) grant no. -PHDF/18-1327. TAROT has been built with the support of the Institut National des Sciences de l'Univers, CNRS, France. TAROT is funded by the CNES and thanks the help of the technical staff of the Observatoire de Haute Provence, OSUPytheas. MP, SK, and MM are supported by European Structural and Investment Fund and the Czech Ministry of Education, Youth and Sports (Projects CZ.02.1.01/0.0/0.0/16 013/0001402, CZ.02.1.01/0.0/0.0/16 013/0001403, and CZ.02.1.01/0.0/0.0/15 003/0000437). NBO, DM, and PG acknowledge financial support from NASA-MUREP-MIRO grant NNX15AP95A, NASA-EPSCoR grant NNX13AD28A, and NSF EiR AST Award 1901296. The GRANDMA collaboration thank the amateur participants to the kilonova-catcher program. The kilonova-catcher program is supported by the IdEx Universite de Paris, ANR-18-IDEX-0001. This research made use of the crossmatch service provided by CDS, Strasbourg. We thank Ulrich Hopp to provide the precise date of observations for AT2019wxt Wendelstein optical observations.

We present the results of reanalysis of old electrophotometric data on RY Scuti obtained at the Abastumani Astrophysical Observatory, Georgia, during 1972–1990 and at the Maidanak Observatory, Uzbekistan, during 1979–1991. Unstable processes in RY Sct from period to period, from month to month and from year to year are revealed. The magnitude of this variation is from hundredths to tenths. Furthermore, periodic changes in the system's light are displayed near the first maximum on timescales of a few years. This is of great interest with regard to some similar variations seen in luminous blue variable stars and, in particular, in S Dor-type stars. This also could be closely related to the question of why RY Sct ejected its nebula.

Three-color photoelectric UBV light curves of the close binary system V448 Cyg obtained at the Abastumani Astrophysical Observatory are analyzed using a new code by Djurasevi. A new value for the ratio of the masses of the components, which is the fundamental parameter for determining the absolute elements of the system, has recently been published. The parameters obtained in our analysis differ substantially from those published previously because the new mass ratio has been employed. The location of the components of V448 Cyg on a mass-logg plot shows that this system, similarly to XZ Cep and V382 Cyg, is in a phase subsequent to a rapid transfer of mass.

The research literature on the star V448 Cyg is reviewed in more detail. An analysis of three color photoelectric observations made at Abastumani is reported in detail with corresponding tables and graphs. In particular, the gaseous structure and evolutionary status of the system are discussed. Newly published spectroscopic data suggest that our light curves might be interpreted by more modern nonclassical methods assuming a new model. Thus, comparing data obtained in this fashion with the new spectroscopic data may help improve the evolutionary status and model for the V448 Cyg system. It is also seems possible to obtain better values of the physical parameters for circumstellar structures and obtain more precise information on the physical conditions in the atmospheres of the stars and on the structure of the circumstellar shells.

We used high-quality Kepler photometry and recent spectroscopic data to investigate the Kepler target KIC 005988140 considering three possible scenario’s: (1) binarity, (2) co-existence of δ Scuti- and γ Doradus-type oscillations, and (3) rotational modulation with spots over the stellar surface. Using spectrum synthesis, we derived improved atmospheric parameters from high-resolution, high signal-to-noise spectra. The star is of spectral type A7.5 IV–III with a metallicity slightly lower than that of the Sun. The Fourier analyses of both the photometric and the spectroscopic data reveal two dominant frequencies – with an integer ratio equal to two – in the low frequency regime. Nine more frequencies located in the typical δ Scuti range were also detected. The mean light and radial velocity curves which are not exactly in anti- phase, show a similar double-wave shape. We therefore suggest on a preliminary basis that the physical cause of the observed light and radial velocity variations is the simultaneous occurrence of (δ Sct-type) pressure modes and stellar rotation coupled to inhomogeneities on the surface of this late A-type star.

Inherited thrombophilia means a predisposition of an individual to thrombosis caused by genetic disorders of homeostasis system. Purpose of the conducted study was to establish the role of point mutations of prothrombin (PGM) - 20210G/A; Factor V Leiden (FVL) - 1691G/A and methylenetetrahydrofolate reductase (MTHFR) - 677C/T genes, i.e. inherited thrombophilia in the pathogenesis of primary and recurrent venous thromboembolism in patients of the Georgian population. The above mentioned mutations were detected by PCR and single nucleotide primer extension reaction, followed by Enzyme Linked Immuno-Sorbent Assay (ELISA) in 93 patients with venous thromboembolism, out of which: 56 patients were diagnosed with unprovoked, primary thromboembolism confirmed by objective studies and 37 patients were diagnosed with recurrent thromboembolism. According to statistical analysis of the results, incidence of FVL mutation in the group of patients with recurrent thrombosis was significantly higher compared to patients with primary thrombosis - respectively 0.21 and 0.44 (p=0.01640.05). It should also be mentioned that homozygous carriage of FVL mutation was confirmed only with patients having recurrent thrombosis. Similar tendency was observed during study of prothrombin gene; however the difference was not statistically significant. Similar tendencies were not observed in case of homozygous carriage of MTHFR gene C677T mutation. Double and triple heterozygous/homozygous carriage of studied mutations (total of 20 cases) was observed in patients of both groups. Distribution of these genotypes in the recurrent thrombosis group was higher compared to patients with primary thrombosis - respectively 27% and 17.9%. Herewith, it should be mentioned that the patients with primary thrombosis were much younger than those with recurrent thrombosis and their age did not exceed 50 years. According to the results obtained by us, it is possible to consider Leiden mutation, especially its homozygous form and double/triple heterozygous/homozygous carriage of the studied mutations as an independent risk factor of development of recurrent thrombosis in the Georgian population and prolong anticoagulation therapy in patients of similar genotype as much as possible to prevent recurrent thrombosis and related complications.

Duration of treatment of venous thromboembolism (VTE) and prevention of its recurrence represent significant problems of contemporary medicine, as the basic method of treatment - anticoagulation is frequently complicated by hemorrhage. Therefore, its duration is strictly defined and depends on existence of risk factors related to recurrence of thrombosis. Purpose of the conducted study was to establish the role of point mutations of prothrombin (PHG) - 20210G/A; Factor V Leiden (FVL) - 1691G/A and methylenetetrahydrofolate reductase (MTHFR) - 677C/T genes, i.e. inherited thrombophilia in the pathogenesis of proximal and distal lower extremity deep vein thrombosis in patients of the Georgian population, as in case of proximal thrombosis there is a higher risk of recurrent thrombosis. The above mutations were detected by PCR and single nucleotide primer extension reaction, followed by Enzyme Linked Immuno-Sorbent Assay (ELISA) in 61 patients with venous thromboembolism of various localizations, out of which: 49 patients were diagnosed with unprovoked proximal thromboembolism confirmed by objective studies and 12 patients were diagnosed with distal thromboembolism. The difference between the groups was evaluated by F (Fisher) precise criterion. According to statistical analysis of the results, incidence of FVL mutation in the group of patients with proximal thrombosis was significantly higher compared to patients with distal thrombosis 0.43 and 0.08 (p=0.0256), respectively. Similar tendencies were observed in case of carriage of prothrombin gene and MTHFR gene mutations, as their presence was higher in the group of patients having proximal thrombosis than in patients with distal thrombosis, however, this difference was not found to be statistically significant. It should be particularly mentioned that double or triple heterozygous or homozygous carriage of studied mutations with various options was confirmed in 15 of 61 patients and the above genotypes were observed only in the group of patients having proximal thrombosis. According to the results obtained from this investigation, it is possible to consider inherited thrombophilia, especially Leiden mutation and double or triple heterozygous and homozygous carriage of studied mutations in the Georgian population as an independent risk factor of development of proximal thrombosis, which on its part, represents one of the risk factors of development of recurrent thrombosis and conduct proper long-standing anticoagulation therapy and take secondary preventive measures in patients of similar genotype to reduce the risk of recurrent thrombosis.

We present observations of Cyg X-1 obtained during the coordinated international campaign “Optical Monitoring of Unique Astrophysical Objects,” carried out in observatories of CIS countries (Georgia, Kazakhstan, Russia, Uzbekistan, and Ukraine) in 1994–1998. The data are presented as a single set, taking into account systematic differences between individual data sets. In total, 2258 UBVR observations were obtained during 407 nights. The observations were carried out simultaneously with X-ray observations at 2–10 keV (ASM/RXTE) and 20–100 keV (BATSE/CGRO), and also with radio observations (in 1997). Our optical data partially overlap the soft X-ray outburst in 1996 (JD 2450200-320) and subsequent hard state, which displayed various types of increases and decreases of the X-ray flux. The 1996 outburst was not accompanied by any optical brightening. However, an orbital light curve corresponding to a tidally distorted star was superimposed on individual flares and brightness dips. For example, in two independent sets of observations, an intense optical flare with amplitude $$0\mathop .\limits^m 04$$ above the quiescent level was detected on JD 2450988, preceding the X-ray flare on JD 2451000-51040. In this time interval, the system displayed chaotic intrinsic variability on a timescale of a day, and flares and brightness dips with amplitude $$0\mathop .\limits^m 10$$ lasting up to several days. The variability power spectra display a predominant secondary period at 147d±2d, which is half the 294d “precessional” period previously found at both X-ray and optical wavelengths. We show that the 147d period dominates in X-ray data (ASM/RXTE) in the quiescent state, or after subtraction of the 1996 outburst radiation from the X-ray light curve. This period is also close to the period of 142d±7d derived from recent radio data. Cross-correlation analysis confirms a significant correlation between the long-term optical and 2–10 keV X-ray variations (without the soft X-ray outburst), with the X-ray variations lagging by 12±2 days.

It is shown that in close binary systems of the Algol type, the companions of which are of spectral type K0- K2 and later, there is a temperature inversion in the surface layers of the photosphere and, as a consequence, the angular distribution of the intensity of escaping radiation for individual small areas proves to differ considerably from the limb- darkening law in the spherically symmetrical case.

Photoelectric UBVR light curves of the gas-darkened variable EM Cep are given. A flare was detected on November 15–16, 1991: while a brightness increase was observed in the R band, a decrease in the star’s U luminosity was observed.

The UBVR photoelectric observations of the variable star EM Cep were made at the Abastumani Astrophysical Observatory, Georgia. On 15–16 November 1991 an unusual flare of this star was revealed. On 17–18 July 2003, flare activity of EM Cep was detected by Turkish astronomers. A suggestion as to the λ Eri-type variability of the star is made.

The size of a telescope determines goals and objects of observations. During the latest decades it becomes more and more difficult to get photometric data of bright stars because most of telescopes of small sizes do not operate already. But there are rather interesting questions connected to the properties and evolution ties between different types of massive stars. Multi-wavelength photometric data are needed for solution of some of them. We are presenting our observational plans of bright Massive X-ray binaries, WR and LBV stars using a small size telescope. All these stars, which are presented in the poster are observational targets of Sopia Beradze’s future PhD thesis. We already have got very interesting results on the reddening and possible future eruption of the massive hypergiant star P Cygni. Therefore, we decided to choose some additional interesting massive stars of different type for future observations. All Massive stars play an important role in the chemical evolution of galaxies because of they have very high mass loss - up to 10−4M⊙/a year. Our targets are on different evolutionary stages and three of them are the members of massive binaries. We plan to do UBVRI photometric observations of these stars using the 48 cm Cassegrain telescope of the Abastumani Astrophisical Observatory.

On the basis of long-term UBV observations of P Cygni, which were made by Eugene Kharadze and Nino Magalashvili between 1951-1983, is evident that P Cygni undergone reddening during those observations. P cygni is a LBV and a supernova impostor. Corrected on the reddening B-V color has values between about -0.4 (at the beginning of 1950-ies) and -0.1 (for the 1980-ies). It means that the star probably had earlier spectral type at the beginning of 20-th century and accordingly, we are witnesses of its evolutionary changes. It means also that on the HR diagram the star moves gradually to the instability strip of LBVs in Outburst. So, if the rate of the reddening of the P Cygni will the same in near future then the star will have the next eruption (or even supernova explosion) after approximately 80-120 years.The long (approximately 1500 d, 1160 d, 760 d, 580 d) quasi-periods and the shorter ones (approximatelly 130 d, 68 d and 15-18 days) were revealed using the above observations.We observed P Cygni on July 23 - October 20, 2014 with the 48 cm Cassegrain telescope and standard B,V,R,I filters. HD 228793 has been used as a comparison star. We revealed that during our observations the star underwent light variations with the mean amplitude of approximately 0.1 magnitudes in all pass-bands and the period of this change was approximately 68 days. There is also a relation between brightness and the Hα EW variability. Therefore, we think that the cause of this behavior may be a variability of rate of the stellar wind that is very strong in this star. Changes in the rate of the stellar wind, on the other hand, maybe due to the pulsation of the star. It seems that quasi-periods of the brightness variability are almost the exact multiples of each other which probably also indicates on pulsation of the star. According to the new photometric observations of 2014 the star continues reddening.

We used high-quality Kepler photometry and spectroscopic data to investigate the Kepler binary candidate KIC 5988140. Using the spectrum synthesis method, we derived the fundamental parameters Teff, log g, [M/H], and v.sini and the abundances. Frequency analyses of both the photometric and the spectroscopic data were performed, revealing the same two dominant frequencies (F_1=0.688 and F_2=0.344 c/d). We also detected in the photometry the signal of nine more, significant frequencies located in the typical range of Delta Scuti pulsation. The light and radial velocity curves follow a similar, stable double-wave pattern which are not exactly in anti-phase but show a relative phase shift of about 0.1 period between the moment of minimum velocity and that of maximum light. We considered three different scenarios: binarity, co-existence of both Gamma Doradus and Delta Scuti pulsations and rotation of the stellar surface with an axisymmetric intensity distribution. However, none of these scenarios is capable of explaining all of the characteristics of the observed variations. We confirm the occurrence of various independent Delta Scuti-type pressure modes in the Kepler light curve. With respect to the low-frequency content, however, we argue that the physical cause of the remaining light and radial velocity variations of this late A-type star remains unexplained by any of the presently considered scenarios., Comment: 9 pages, 12 encapsulated Postscript figures. Table~A.1 is available in electronic form only, in press

GRANDMA is an international project that coordinates telescope observations of transient sources with large localization uncertainties. Such sources include gravitational wave events, gamma-ray bursts and neutrino events. GRANDMA currently coordinates 25 telescopes (70 scientists), with the aim of optimizing the imaging strategy to maximize the probability of identifying an optical counterpart of a transient source. This paper describes the motivation for the project, organizational structure, methodology and initial results., 8 pages, to appear in Revista Lexicana de Astronomia y Astrofisica Conference Series