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Full list of authors: Buckley, D. A. H.; Bagnulo, S.; Britto, R. J.; Mao, J.; Kann, D. A.; Cooper, J.; Lipunov, V.; Hewitt, D. M.; Razzaque, S.; Kuin, N. P. M.; Monageng, I. M.; Covino, S.; Jakobsson, P.; van der Horst, A. J.; Wiersema, K.; Böttcher, M.; Campana, S.; D'Elia, V.; Gorbovskoy, E. S.; Gorbunov, I.; Groenewald, D. N.; Hartmann, D. H.; Kornilov, V. G.; Mundell, C. G.; Podesta, R.; Thomas, J. K.; Tyurina, N.; Vlasenko, D.; van Soelen, B.; Xu, D., We report on results of spectropolarimetry of the afterglow of the long gamma-ray burst GRB 191221B, obtained with SALT/RSS and VLT/FORS2, as well as photometry from two telescopes in the MASTER Global Robotic Network, at the MASTER-SAAO (South Africa) and MASTER-OAFA (Argentina) stations. Prompt optical emission was detected by MASTER-SAAO 38 s after the alert, which dimmed from a magnitude (white-light) of ∼10-16.2 mag over a period of ∼10 ks, followed by a plateau phase lasting ∼10 ks and then a decline to ∼18 mag after 80 ks. The light curve shows complex structure, with four or five distinct breaks in the power-law decline rate. SALT/RSS linear spectropolarimetry of the afterglow began ∼2.9 h after the burst, during the early part of the plateau phase of the light curve. Absorption lines seen at ∼6010 and 5490 Å are identified with the Mg ii 2799 Å line from the host galaxy at z = 1.15 and an intervening system located at z = 0.96. The mean linear polarization measured over 3400-8000 Å was ∼1.5 per cent and the mean equatorial position angle (θ) was ∼65°. VLT/FORS2 spectropolarimetry was obtained ∼10 h post-burst, during a period of slow decline (α = -0.44), and the polarization was measured to be p = 1.2 per cent and θ = 60°. Two observations with the MeerKAT radio telescope, taken 30 and 444 d after the GRB trigger, detected radio emission from the host galaxy only. We interpret the light curve and polarization of this long GRB in terms of a slow-cooling forward shock. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society., Some of the observations presented here were obtained with SALT under programme 2018-2-LSP-001 (PI: DAHB), which is supported by Poland under grant no. MNiSW DIR/WK/2016/07. Based on observations collected at the European Southern Observatory under ESO programme 0104.D-0600(C). DAHB and JT acknowledge support through the National Research Foundation (NRF) of South Africa. MB is supported by the South African Research Chairs Initiative (grant no. 64789) of the Department of Science and Innovation and the NRF.5 DMH acknowledges financial support from the NRF and the SAAO. SR is partially supported by NRF with grant no. 111749 (CPRR) and by a University of Johannesburg Research Council grant. DAK acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). NPMK acknowledges support by the UK Space Agency. MASTER (equipment) is supported by Lomonosov Moscow State University Development Program. VL and DV are supported by RFBR grant 19-29-11011. CGM acknowledges financial support from Hiroko and Jim Sherwin. We thank the Director and staff of SARAO for supporting our MeerKAT DDT observation. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory (SARAO), which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. Based on observations made with the SALT and the MeerKAT radio telescope array., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

The differential image motion monitor (DIMM) is widely used to measure the atmospheric optical turbulence (OT) integral over the line of sight. However, it is known that because of the wave propagation effect, the DIMM’s sensitivity falls with the distance to the turbulent layer and the variance of differential image motion is only approximately proportional to the OT integral. In this paper, we study this problem using the formalism of so-called weighting functions (WFs). We develop a method for calculating these WFs, including the case of the wide spectral band of detected radiation. The effect of underestimating the OT integral for different DIMM devices involved in previous site-testing campaigns is estimated using real measurements of OT vertical profiles. For instruments with small apertures (4–6 cm), the underestimation is ≈10 per cent, whereas for larger devices with apertures of 8–10 cm, the underestimation is less than 5 per cent, on average. This leads to a negative bias in seeing estimation of 7 and 3 per cent, respectively.

2070 unique, homogeneous photometric and polarization observations of the microquasar in a binary system with a black hole V404 Cyg/GS2023+338 obtained in 2015 with the MASTER global network of robotic telescopes (16 robotic telescopes located at eight points on the Earth in Russia, Spain, South Africa, and Argentina) are presented. MASTER was the first telescope network to obtain optical observations of the microquasar after its gamma-ray outburst in 2015. Observations were carried out from 18:34:09 UT on June 15, 2015 until December 2015 in four polarizations and in the four standard BV RI filters. The paper presents the results of these observations and a comparative analysis of optical and X-ray data. The observations confirm the previously discovered super-long delays of the optical radiation relative to the X-ray outbursts. Possible mechanisms causing the delay in the optical variations relative to the X-ray variations are discussed. Variability of the optical polarization discovered earlier is confirmed another similar episode reported.

The concept of a multi-functional astronomical complex as applied to robotic astronomy networks and systems is formulated. The practical realization of this concept in the MASTER global network of robotic telescopes of Moscow State University is described. The dynamically integrated MASTER database, which transforms a network of robotic telescopes into a robotic network, is described. Real, multi-channel astronomical observations obtained on the MASTER global network are used to show the effective application of this concept. The MASTER global network is continuously participating in multi-wavelength and multi-channel observations aimed at studying astrophysical sources located in extreme conditions, including the sources of gravitational waves registered by the LIGO/VIRGO detectors, of high-energy neutrinos detected by IceCube and ANTARES, and of fast radio bursts (FRBs) and gamma-ray bursts (GRBs). The MASTER network provided the most extensive survey of the first error field for the LIGO gravitational-wave outburst GW 150914 (5000 square degrees) and carried out the first independent localization of the gravitational-wave event GW170817. TheMASTER network has also discovered more than 1600 optical transients with various physical natures. Data obtained with the MASTER network have been used to provide pointing information to major ground-based and space-based telescopes.

The results of experiments onboard the Lomonosov satellite on observing natural and technogenic space hazards including electromagnetic transients and space debris are discussed. A new space project Universat-SOCRAT being developed by Moscow State University is also discussed. The project aims to create a constellation of small satellites for real-time monitoring of the radiation environment and potentially hazardous objects of natural (asteroids, meteoroids) and technogenic origin (space debris) in near-Earth space, and such phenomena as cosmic and atmospheric gamma-ray bursts and optical and ultraviolet radiation flashes from Earth’s atmosphere.

The Multimessenger GW170817 / GRB170817A discovery of the merger of two neutron stars on 17th August 2017 accompanied by a gamma-ray burst and an optical kilonova event is a triumph of the ideas about the evolution of the baryon component in the Universe. Despite the current uniqueness of this observation, the variety of the experimental data obtained makes it possible right now to draw important theoretical conclusions about the origin of the double neutron star, its merger, and the subsequent flare-up of electromagnetic radiation. We demonstrate that the discovery of the merger at a distance of 40 Mpc is entirely consistent with the very first calculations of the Scenario Machine ( Lipunov et al. 1987 ). In modern terms, the predicted rate is ∼10 000 Gpc−3.

The new space project of M. V. Lomonosov Moscow State University on elaboration of multiple satellites for real time monitoring in the near-Earth space of radiation environment, natural (asteroids, meteoroids) and artificial (space debris) potentially dangerous objects, electromagnetic transients, such as cosmic gamma ray bursts, terrestrial gamma ray flashes, optical and ultraviolet bursts in the Earth atmosphere is presented. It is intended to install on the satellites the following instruments for space monitoring of dangerous objects and hazards: spectrometers of electrons and protons, complex of instruments for study of transient electromagnetic phenomena including gamma ray spectrometer, detectors of ultraviolet and optical emission and wide-field optical cameras. Successful implementation of the project for the first time in the world allows realization of a space system prototype for monitoring and preventing of space hazards for both ongoing and planned space missions, and also for aircraft flying in the upper atmosphere. There are also discussed results of experiments on-board Lomonosov in view of good experience of wide field camera use for monitor observations in space. These results formed the base of scientific program for the new project Universat- SOCRAT.

The study of cosmic gamma ray bursts (GRBs) is one of the main goals of the Lomonosov space mission. The main advantage of this mission is simultaneous multiwavelength observations of GRBs covering the optical, X-ray and gamma-ray ranges. The mission payload includes the GRB monitor BDRG, wide-field optical cameras SHOK, and the UFFO instrument. Data are recorded mainly by the event trigger provided by the BDRG instrument, which measures the spectral and temporal properties of the burst in the energy range 10–3000 keV. The BDRG instrument also provides estimation of the source coordinates by comparing the readings of three differently directed detectors with an accuracy of several degrees. Wide-field SHOK optical cameras have a field of view of ~20° × 40°. They fix a set of images with a frequency of about five frames per second prior to the trigger and another set immediately after the trigger. The UFFO instrument includes the UBAT telescope with a coded mask for measurements in hard X-ray and soft gamma-ray ranges and an optical telescope with a slewing mirror (SMT) that can be directed on the GRB source for a time ~1 s for measuring GRB prompt emission in the early stages. In response to an BDRG trigger signal, the real-time data on a detected GRB are transmitted to the Earth via Globalstar network to the Gamma-ray Coordinates Network (GCN) and ground-based observatories. During observations on the Lomonosov satellite, 20 gamma-ray bursts were detected and catalogued. Several gamma-ray bursts were also detected in the Vernov satellite experiment. An example of such an event is given., Financial support for this work was provided by the Ministry of Education and Science of the Russian Federation, project no RFMEFI60717X0175.

We present the earliest astronomical observation of a high energy neutrino error box in which its variability was discovered after high-energy neutrinos detection. The one robotic telescope of the MASTER global international network (Lipunov et al. 2010) automatically imaged the error box of the very high-energy neutrino event IceCube-170922A. Observations were carried out in minute after the IceCube-170922A neutrino event was detected by the IceCube observatory at the South Pole. MASTER found the blazar TXS 0506+056 to be in the off-state after one minute and then switched to the on-state no later than two hours after the event. The effect is observed at a 50-sigma significance level. Also we present own unique 16-years light curve of blazar TXS 0506+056 (518 data set)., 17 pages, 3 figures, 1 Table accepted to The Astrophysical Journal Letters

Based on the measurements performed from 2007 to 2015 at the summit of Mount Shatdzhatmaz adjacent to the 2.5-m telescope at the Caucasus Observatory of the SAI MSU, we have determined the statistical characteristics of basic meteorological parameters: the ambient air temperature, the ground wind speed, and the relative humidity. The stability of these parameters over the entire period of our measurements and their variations within an annual cycle have been studied. The median temperature on clear nights is +3.2°C, although there are nights with a temperature below −15°C. The typical ground wind speed is 3 m s−1; the probability of a wind stronger than 10 m s−1 does not exceed 2%. The losses of observing time due to high humidity are maximal in the summer period but, on the whole, are small over a year, less than 10%. We have estimated the absolute water vapor content in the atmosphere, which is especially important for infrared observations. Minimum precipitablewater vapor is observed in December–February; the median value over these months is 5 mm. We additionally provide the wind speeds at various altitudes above the ground (from 1 to 16 km) that we obtained when measuring the optical turbulence. We present the results and technique of our measurements of the annual amount of clear night astronomical time, which is, on average, 1320 h, i.e., 45% of the possible one at the latitude of the observatory. The period from mid-September to mid-March accounts for about 70% of the clear time. A maximum of clear skies is observed in November, when its fraction reaches 60% of the possible astronomical night time.

We present comprehensive multiwavelength radio to X-ray observations of GRB 181201A spanning from $\approx150$ s to $\approx163$ days after the burst, comprising the first joint ALMA-VLA-GMRT observations of a gamma-ray burst (GRB) afterglow. The radio and mm-band data reveal a distinct signature at $\approx3.9$ days, which we interpret as reverse shock (RS) emission. Our observations present the first time that a single radio-frequency spectral energy distribution can be decomposed directly into RS and forward shock (FS) components. We perform detailed modeling of the full multiwavelength data set, using Markov Chain Monte Carlo sampling to construct the joint posterior density function of the underlying physical parameters describing the RS and FS synchrotron emission. We uncover and account for all degeneracies in the model parameters. The joint RS-FS modeling reveals a weakly magnetized ($\sigma\approx3\times10^{-3}$), mildly relativistic RS, from which we derive an initial bulk Lorentz factor of $\Gamma_0\approx103$ for the GRB jet. Our results support the hypothesis that low-density environments are conducive to the observability of RS emission. We compare our observations to other events with strong RS detections, and find a likely observational bias selecting for longer lasting, non-relativistic reverse shocks. We present and begin to address new challenges in modeling posed by the present generation of comprehensive, multi-frequency data sets., Comment: Accepted version

This paper presents data on the simultaneous and complementary observations of the gamma-ray burst (GRB) GRB 161017A for optical, X-ray, and gamma wavelengths obtained by the Russian multi-messenger Lomonosov space observatory and supplemented by additional data from the Swift satellite as well as the ground-based MASTER Global Robotic Net and the 10 m Gran Telescopio Canarias. Multifrequency spectra of this very powerful explosion indicate that it originated at a distance of 10 billion light years from Earth. Here, we present the results of the prompt, early, and afterglow optical observations. The light curves and spectra suggest that the prompt optical and high-energy emissions occur in the same region near the GRB source. © 2018. The American Astronomical Society. All rights reserved., Analysis of the gamma-ray events observation during the BDRG experiment on board the Lomonosov satellite was fulfilled with the financial support of Ministry of Education and Science of Russia, grant No. RFMEFI60717X0175. A.J.C.T. acknowledges the Spanish Ministry Program AYA 2015-71718-R. MASTER Global Robotic Net is supported in part by the Development Program of Lomonosov Moscow State University. I.H.P. acknowledges National Research Foundation of Korea for Nos. 2018R1A2A1A05022685 and 2017K1A4A3015188. S.J. acknowledges the support of the Korea Basic Science Research Program through NRF-2018R1D1A1B07048993. This work was also supported in part by the RFBR grant 17-52-80133 and by Russian Science Foundation (RSF) grant 16-12-00085 (data analysis, interpretation, and discussion).

The results of observations with the MASTER-SHOK robotic wide-field optical cameras onboard the Lomonosov Space Observatory carried out in 2016 are presented. In all, the automated transient detection system transmitted 22 181 images of moving objects with signal-to-noise ratios greater than 5 to the Earth. Approximately 84% of these images are identified with well-known artificial Earth satellites (including repeated images of the same satellite) and fragments of such satellites (space debris), according to databases of known satellites. The remaining 16% of the images are relate to uncatalogued objects. This first experience in optical space-based monitoring of near-Earth space demonstrates the high efficiency and great potential of using large-aperture cameras in space, based on the software and technology of the MASTER robotic optical complexes (the Mobile Astronomical System of TElescope-Robots (MASTER) global network of robotic telescopes of Lomonosov Moscow State University)., Comment: 10 pages, 5 figures, published in Astronomy Reports

Onboard the spacecraft Lomonosov is established two fast, fixed, very wide-field cameras SHOK. The main goal of this experiment is the observation of GRB optical emission before, synchronously, and after the gamma-ray emission. The field of view of each of the cameras is placed in the gamma-ray burst detection area of other devices located onboard the “Lomonosov” spacecraft. SHOK provides measurements of optical emissions with a magnitude limit of $\sim 9\mbox{--}10^{m}$ on a single frame with an exposure of 0.2 seconds. The device is designed for continuous sky monitoring at optical wavelengths in the very wide field of view (1000 square degrees each camera), detection and localization of fast time-varying (transient) optical sources on the celestial sphere, including provisional and synchronous time recording of optical emissions from the gamma-ray burst error boxes, detected by the BDRG device and implemented by a control signal (alert trigger) from the BDRG. The Lomonosov spacecraft has two identical devices, SHOK1 and SHOK2. The core of each SHOK device is a fast-speed 11-Megapixel CCD. Each of the SHOK devices represents a monoblock, consisting of a node observations of optical emission, the electronics node, elements of the mechanical construction, and the body.

International audience; This paper presents the first investigation results of possible coincidences of optical transients in the MASTERglobal robotic telescope net database with the localization regions of VHE and UHE neutrino alert events fromANTARES and IceCube observatories. MASTER is the first robotic telescopic system in Russia, dedicated tooptical observation and registration of the most energetic and fastest explosive processes in the Universe. Thegoal is a deeper and more thorough study of space and time coincidences of the MASTER optical transientsand high energy neutrinos.

UFFO Burst Alert and Trigger telescope (UBAT) is the X-ray trigger telescope of UFFO/Lomonosov to localize X-ray source with coded mask method and X-ray detector. Its X-ray detector is made up of 36 8×8 pixels Yttrium OxyorthoSilicate (Y2SiO5:Ce, YSO) scintillation crystal arrays and 36 64-channel Multi-Anode PhotoMultiplier Tubes (MAPMTs) for space mission. Its effective detection area is 161cm2 and energy range is several keV to 150 keV. It was successfully launched in April 28, 2016. In several calibration run, we got several X-ray background data. We already knew X-ray background flux is 2-3 counts/cm2/sec in space. However our X-ray background data shows approximately 7-8 times higher than what we know. There are many candidates to explain high X-ray background count in space. One of candidates is cosmic ray. We will report cosmic ray effect on the X-ray detector using YSO scintillation crystal arrays in space.

The Slewing Mirror Telescope (SMT) is the first orbital instrument, using motorized mirror for observations of the space, designed to shed light on first seconds of Gamma-Ray Bursts (GRBs) prompt UV/optical emission. The SMT is main component of the Ultra-Fast Flash Observatory (UFFO). Once GRB is detected by UFFO X-ray coded mask camera, SMT turns its motorized mirror within seconds to observe optical and UV emission of GRB. After several years of delay on its launch, UFFO was finally launched in 28 April 2016. Launch took place onboard Lomonosov satellite from new Russian kosmodrom Vostochny. Several space tests have been performed during that period, which proved the concept of SMT and gave precise values of SMT sensitivity and resolution. For the first time in the space observations, motorized mirror system is able to trace objects despite the drift of telescope FOV due to satellite orbital movement.

GRB study is one of the main goals of the Lomonosov space mission. Multimessenger GRB observation is the only way of progress achievement in their study. The Lomonosov satellite is the first space mission in which the multi-wave length observations of GRBs are realized in real time without necessity of optical instrument re-orientation on GRB monitor trigger. The mission payload includes the GRB monitor BDRG, wide field optical cameras SHOK and UFFO instrument consisting of X-ray imaging telescope UBAT and UV slewing mirror telescope SMT. Two wide field cameras are placed in such a way that their fields of view (FOV) are overlapped by the GRB monitor detector FOVs. This allows the simultaneous GRB observations in gammas and optics in all-time scale of event evolution including obtaining optical light curves of prompt emission as well as of precursors. The real time data transfer to the GCN for detected GRB is realized as well as operative control of BDRG data on triggers from ground based facilities including neutrino and gravitation wave detectors. The GRB catalogue is presented in this report, also those events, for which information was obtained in different bands, are discussed in details.

Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase1, 2, 3, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent—consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source3. By contrast, optical4, 5, 6 and γ-ray7, 8, 9 observations during the prompt phase have led to discordant and often controversial10, 11, 12 results, and no definitive conclusions have been reached regarding the origin of the prompt radiation or the configuration of the magnetic field. Here we report the detection of substantial (8.3 ± 0.8 per cent from our most conservative simulation), variable linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt γ-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the jet, closer to its central black hole, and show that the prompt phase is produced via fast-cooling synchrotron radiation in a large-scale magnetic field that is advected from the black hole and distorted by dissipation processes within the jet.

The Advanced LIGO observatory recently reported the first direct detection of gravitational waves predicted by Einstein (1916). We report on the first optical observations of the Gravitational Wave (GW) source GW150914 error region with the Global MASTER Robotic Net. We detected several optical transients, which proved to be unconnected with the GW event. Our result is consistent with the assumption that gravitational waves were produced by a binary black hole merger. The detection of the event confirmed the main prediction of the population synthesis performed with the "Scenario Machine" formulated in Lipunov1997b., 11 pages, 7 figures, 4 tables

One of the goals of the Lomonosov satellite designed by scientists of Moscow State University is to study the prompt emission of cosmic gamma-ray bursts. This paper describes the gamma-ray burst monitor in the gamma-ray range (the BDRG instrument) and the wide-field optical cameras (the SHOK instrument) for detecting both the gamma-ray burst prompt emission and its precursors.

Ultra-Fast Flash Observatory pathfinder(UFFO-p) was launched onboard Lomonosov on 28th of April, 2016, and now is under various types of calibration for detection of Gamma Ray Bursts (GRBs). Since last September UFFO-p has taken X-ray data in space with UFFO Burst Alert & Trigger telescope (UBAT), those X-rays are mostly diffused backgrounds however, the rate turns out to be higher than expected by a factor of three. We assumed cosmic rays can contribute by making the count rate higher. We did such a simulation to investigate the effect of cosmic rays. In December 2016, we irradiated fragmented high energy heavy ions at CERN on the UBAT detector. We will report the result of comparison between simulation and beam test.

We report the discovery and multicolor (VRIW) photometry of a rare explosive star MASTER OT J004207.99+405501.1 - a luminous red nova - in the Andromeda galaxy M31N2015-01a. We use our original light curve acquired with identical MASTER Global Robotic Net telescopes in one photometric system: VRI during first 30 days and W (unfiltered) during 70 days. Also we added publishied multicolor photometry data to estimate the mass and energy of the ejected shell, and discuss the likely formation scenarios of outbursts of this type. We propose the interpretation of the explosion, that is consistent with the evolutionary scenario where star merger is a natural stage of the evolution of close-mass stars and may serve as an extra channel for the formation of nova outbursts., Comment: 16 pages, 9 figures, 2 tables, accepted to MNRAS

The study of GRB prompt emission (PE) is one of the main goals of the Lomonosov space mission, which is being prepared at Moscow State University. The GRB monitor (BDRG) and the wide-field optical cameras (SHOK) are intended for detection of GRB prompt emission as well as optical counterparts. The BDRG instrument consists of three identical NaI(Tl)/CsI(Tl) (13.0 × 2.0cm ) phoswich detectors, whose axes determine the Cartesian coordinate system. This allows to localize any GRB source on the sky by means of the count rate seen by each detector with an accuracy of ~2 deg. The SHOK instrument consists of two identical wide-field cameras (WFC) directed in such a way that the field of view (FOV) of each WFC overlaps by the corresponding BDRG FOV, which produces a trigger on the WFC in case of a GRB detection. With this setup, the GRB prompt light curve will be obtained in the visible without any delay with respect to gamma-rays, which is crucial for a GRB central engine understanding.

On 2015 June 15 the Swift space observatory discovered that the Galactic black hole candidate V404 Cyg was undergoing another active X-ray phase, after 25 years of inactivity (Barthelmy et al. 2015). Twelve telescopes of the MASTER Global Robotic Net located at six sites across four continents were the first ground based observatories to start optical monitoring of the microquasar after its gamma-ray wakeup at 18h 34m 09s U.T. on 2015 June 15 (Lipunov et al. 2015). In this paper we report, for the first time, the discovery of variable optical linear polarization, changing by 4-6% over a timescale of approximately 1 h, on two different epochs. We can conclude that the additional variable polarization arisies from the relativistic jet generated by the black hole in V404Cyg. The polarization variability correlates with optical brightness changes, increasing when the flux decreases., 10 pages, 1 figures, 4 tables, accepted for publication in the The Astrophysical Journal

The Advanced LIGO observatory recently reported (Abbott et al., 2016a) the first direct detection of gravitational waves predicted by Einstein (1916). The detection of this event was predicted in 1997 on the basis of the Scenario Machine population synthesis calculations (Lipunov et al., NewA, 2, 43). Now we discuss the parameters of binary black holes and event rates predicted by different scenarios of binary evolution. We give a simple explanation of the big difference between detected black hole masses and the mean black hole masses observed in of X-ray Nova systems. The proximity of the masses of the components of GW150914 is in good agreement with the observed initial mass ratio distribution in massive binary systems, as is used in Scenario Machine calculations for massive binaries., 13 pages, 4 figures

The accuracy of ground-based astronomical photometry is limited by two factors: photon statistics and stellar scintillation arising when star light passes through Earth's atmosphere. This paper examines the theoretical role of the outer scale $L_0$ of the optical turbulence (OT) which suppresses the low-frequency component of scintillation. It is shown that for typical values of $L_0 \sim 25 - 50$ m, this effect becomes noticeable for a telescopes of diameter around 4 m. On extremely large, $30 - 40$ m, telescopes with exposures longer than a few seconds, the inclusion of the outer scale in the calculation reduces the scintillation power by more than a factor of 10 relative to conventional estimates. The details of this phenomenon are discussed for various models of non-Kolmogorov turbulence. Also, a quantitative description of the influence of the telescope central obscuration on the measured scintillation noise is introduced and combined with the effect of the outer scale. Evaluation of the scintillation noise on the future TMT and E-ELT telescopes, predicts an amplitude of approximately $10 \mumag$ for a 60 s exposures.

We present results of the prompt, early, and afterglow optical observations of five gamma-ray bursts, GRBs 100901A, 100902A, 100905A, 100906A, and 101020A, made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II net), the 1.5-m telescope of Sierra-Nevada Observatory, and the 2.56-m Nordic Optical Telescope. For two sources, GRB 100901A and GRB 100906A, we detected optical counterparts and obtained light curves starting before cessation of gamma-ray emission, at 113 s and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted with two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. More detailed analysis of GRB 100901A and GRB 100906A supplemented by Swift data provides the following results and indicates different origins of the prompt optical radiation in the two bursts. The light curves patterns and spectral distributions suggest a common production site of the prompt optical and high-energy emission in GRB 100901A. Results of spectral fits for GRB 100901A in the range from the optical to X-rays favor power-law energy distributions with similar values of the optical extinction in the host galaxy. GRB 100906A produced a smoothly peaking optical light curve suggesting that the prompt optical radiation in this GRB originated in a front shock. This is supported by a spectral analysis. We have found that the Amati and Ghirlanda relations are satisfied for GRB 100906A. An upper limit on the value of the optical extinction on the host of GRB 100906A is obtained.

Whole atmosphere seeing \beta_0 is the most important parameter in site testing measurements. Estimation of the seeing from a variance of differential image motion is always biased by a non-zero DIMM exposure, which results in a wind smoothing. In the paper, the wind effects are studied within short exposure approximation, i.e. when the wind shifts turbulence during exposure by distance lesser than device aperture. The method of correction for this effect on the base of image motion correlation between adjacent frames is proposed. It is shown that the correlation can be used for estimation of the mean wind speed V_2 and atmospheric coherence time \tau_0. Total power of longitudinal and transverse image motion is suggested for elimination of dependence on the wind direction. Obtained theoretical results were tested on the data obtained on Mount Shatdjatmaz in 2007--2010 with MASS/DIMM device and good agreement was found.

The atmospheric scintillation of stars is the main limitation of the accuracy of ground-based photometry of astronomical objects. This becomes particularly noticeable for a study of a variability with amplitudes on the order to thousandths of stellar magnitude or less. We examined the problem of the colour scintillation --- fluctuations of difference between light intensities measured simultaneously in two different photometric bands. Relations between the colour scintillation power (index) and the atmospheric turbulence, telescope diameter and the characteristics of the photometric channels are derived. Asymptotic dependencies for large telescopes (1--10 m) are obtained that allow to predict the value of the colour scintillation for a particular telescope and detector. It is shown that the colour scintillation index is ~D^{-3} for measurements with both short (milliseconds) and long (seconds) exposures. The impact of the atmospheric dispersion which amplifies colour scintillation away from the zenith is estimated. We show that colour scintillation in the long-exposure regime depends strongly on the wind direction in the upper atmosphere.

The effect of stellar scintillation on the accuracy of photometric measurements is analyzed. We obtain a convenient form of estimaton of this effect in the long exposure regime, when the turbulence shift produced by the wind is much larger than the aperture of the telescope. A simple method is proposed to determine index $S_3$ introduced by perture of the Kenyon et al. (2006), directly from the measurements with the Multi Aperture Scintillation Sensor (MASS) without information on vertical profile of the wind. The statistics $S_3$ resulting from our campaign of 2005 -- 2007 at Maidanak observatory is presented. It is shown that these data can be used to estimate high-altitude winds at pressure level 70 -- 100 mbar. Comparison with the wind speed retrieved from the NCEP/NCAR global models shows a good agreement. Some prospects for retrieval of the wind speed profile from the MASS measurements are outlined., Comment: 11 pages, 9 figures, accepted for publication in Astronomy Letters

We present the first results of the site testing performed at Mt.~Shatdzhatmaz at Northern Caucasus, where the new Sternberg astronomical institute 2.5-m telescope will be installed. An automatic site monitor instrumentation and functionality are described together with the methods of measurement of the basic astroclimate and weather parameters. The clear night sky time derived on the basis of 2006 -- 2009 data amounts to 1340 hours per year. Principle attention is given to the measurement of the optical turbulence altitude distribution which is the most important characteristic affecting optical telescopes performance. For the period from November 2007 to October 2009 more than 85\,000 turbulence profiles were collected using the combined MASS/DIMM instrument. The statistical properties of turbulent atmosphere above the summit are derived and the median values for seeing $\beta_0 = 0.93$~arcsec and free-atmosphere seeing $\beta_{free} = 0.51$~arcsec are determined. Together with the estimations of isoplanatic angle $\theta_0 = 2.07$~arcsec and time constant $\tau_0 = 2.58 \mbox{ ms}$, these are the first representative results obtained for Russian sites which are necessary for development of modern astronomical observation techniques like adaptive optics.

The MASTER robotic telescope has obtained the first optical images of GRB 060926. We have discovered an optical flare from GRB 060926, a recurrent brightening that closely follows its behavior in the X-ray range. We have determined the spectral slope for GRB 060926 from the X-ray to optical range in the first minutes. Based on the spinar model, we show that the parameters of the optical and X-ray flares suggest that the gamma-ray burst resulted from the core collapse of a 7M ⊙ star with an initial effective Kerr parameter of 7.6 and an initial magnetic-to-gravitational energy ratio of 10−4.

A new description of the registration of events by a counter with a dead time based on a nonclassical, quasi-binomial distribution is proposed. A description of the type of dead time via the continuous parameter y is introduced. It is shown based on this approach that the distribution of events registered by an non-extendable counter (y = 1) can be described by a generalized Poisson distribution. It is shown for various types of counters that the distribution of registered events will be indistinguishable from a generalized Poisson distribution if the number of measurements is ≲ 106. Formulas that can be used to determine the initial flux of events from the detected flux and vice versa are derived. The behavior of the non-Poisson coefficient as a function of the non-linearity is discussed. All the analytical results obtained are tested using numerical simulations.

We report early optical linear polarization observations of two gamma-ray bursts made with the MASTER robotic telescope network. We found the minimum polar- ization for GRB150301B to be 8% at the beginning of the initial stage, whereas we detected no polarization for GRB150413A either at the rising branch or after the burst reached the power-law afterglow stage. This is the earliest measurement of the polarization (in cosmological rest frame) of gamma-ray bursts. The primary intent of the paper is to discover optical emission and publish extremely rare (unique) high- quality light curves of the prompt optical emission of gamma-ray bursts during the non-monotonic stage of their evolution. We report that our team has discovered the optical counterpart of one of the bursts, GRB150413A., Comment: accepted, MNRAS, 2015

The photometric sky quality of Mt. Shatdzhatmaz, the site of Sternberg Astronomical Institute Caucasian Observatory 2.5 m telescope, is characterized here by the statistics of the night-time sky brightness and extinction. The data were obtained as a by-product of atmospheric optical turbulence measurements with the MASS (Multi-Aperture Scintillation Sensor) device conducted in 2007--2013. The factors biasing night-sky brightness measurements are considered and a technique to reduce their impact on the statistics is proposed. The single-band photometric estimations provided by MASS are easy to transform to the standard photometric bands. The median moonless night-sky brightness is 22.1, 21.1, 20.3, and 19.0 mag per square arcsec for the $B$, $V$, $R$, and $I$ spectral bands, respectively. The median extinction coefficients for the same photometric bands are 0.28, 0.17, 0.13, and 0.09 mag. The best atmospheric transparency is observed in winter., Comment: 10 pages, 9 figures, accepted for publication in MNRAS

Several site-testing programs and observatories currently use combined MASS-DIMM instruments for monitoring parameters of optical turbulence. The instrument is described here. After a short recall of the measured quantities and operational principles, the optics and electronics of MASS-DIMM, interfacing to telescopes and detectors, and operation are covered in some detail. Particular attention is given to the correct measurement and control of instrumental parameters to ensure valid and well-calibrated data, to the data quality and filtering. Examples of MASS-DIMM data are given, followed by the list of present and future applications.

Astronomical seeing is quantified by a single parameter, turbulence integral, in the framework of the Kolmogorov turbulence model. This parameter can be routinely measured by a Differential Image Motion Monitor, DIMM. A new instrument, Multi-Aperture Scintillation Sensor (MASS), permits to measure the seeing in the free atmosphere above ~0.5km and, together with a DIMM, to estimate the ground-layer seeing. The absolute accuracy of both methods is studied here using analytical theory, numerical simulation, and experiments. A modification of the MASS data processing to compensate for partially saturated scintillation is developed. We find that the DIMM can be severely biased by optical aberrations (e.g. defocus) and propagation. Seeing measurements with DIMM and MASS can reach absolute accuracy of ~10% when their biases are carefully controlled. Pushing this limit to 1% appears unrealistic because the seeing itself is just a model-dependent parameter of a non-stationary random process.