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A regular monodisperse flow of spherical microtargets of solid hydrogen or deuterium with a variable diameter of several tens of micrometers and a frequency from several tens to several hundreds of kilohertz is in demand as internal targets in physical experiments at accelerators. The paper is devoted to the modification and launching of a prototype cryogenic corpuscular hydrogen target in which the gas entering the facility is transformed into a flow of spherical microtargets. Processes of cryogenic cooling and liquefaction of the gas, formation of a liquid microjet, and its controlled monodisperse disintegration into equal-sized drops are realized in the target, and they are followed by freezing of the drops and formation of microtargets upon injection into vacuum. The target prototype is composed of the cryogenic, vacuum, and gas systems as well as the systems for control and optical diagnostics of microtarget parameters. The modified target prototype provided monodisperse regimes of generation of microtargets with a diameter of 20–50 μm at a generation frequency of 260–465 kHz. [ABSTRACT FROM AUTHOR]

We present the results of our UBVRI CCD photometry for the second brightest supernova of 2009, SN 2009nr, discovered during a sky survey with the telescopes of the MASTER robotic network. Its light and color curves and bolometric light curves have been constructed. The light-curve parameters and the maximum luminosity have been determined. SN 2009nr is shown to be similar in light-curve shape and maximum luminosity to SN 1991T, which is the prototype of the class of supernovae Ia with an enhanced luminosity. SN 2009nr exploded far from the center of the spiral galaxy UGC 8255 and most likely belongs to its old halo population. We hypothesize that this explosion is a consequence of the merger of white dwarfs. [ABSTRACT FROM AUTHOR]

The paper presents the method for detecting exoplanets in the image archive obtained by telescopes of the MASTER Global Network since 2002. The unique archive represents homogeneous photometric data obtained over 20 years for the northern (MASTER-Amur, MASTER-Tunka, MASTER-Kislovodsk, M-ASTER-Tavrida, MASTER-IAC, MASTER-OAGH) and 11 years for the southern sky (MASTER-OAFA, MASTER-SAAO). Algorithm of gamma-ray burst error box observation on the MASTER wide-field telescopes make it possible to detect transit phenomena and find exoplanets in archival data. The article presents the results of a photometric analysis of the TESS exoplanet candidate TOI–3570.01. [ABSTRACT FROM AUTHOR]

In the PANDA experiment of the FAIR project, it is proposed to use internal targets based on the hydrogen isotopes that provide a monodisperse regime of flow generation of solid spherical pellets with the diameter from 15–40 µm with the frequency from several tens of to several hundred kilohertz. The process for generating the pellets in such facilities includes the cooling, liquefying, and disintegration into drops of the liquid hydrogen jet directed vertically downwards; freezing of the jet when expiring with acceleration into vacuum; and its transport through the vacuum path into the region of interaction with the antiproton beam. For the effective control of the systems of the setup and for the adjustment of generation of pellets, an automatization and control system is developed combining the devices for measurement and control of pellet parameters (temperature, pressure, hydrogen flow, and piezoelectric generator frequency) and the optical diagnostics in a unified computational network. For data exchange between the devices, the TCP/IP Sockets and Modbus TCP protocols are used. [ABSTRACT FROM AUTHOR]

This paper considers latest highlights in simultaneous and follow-up optical observations of high energy astrophysical phenomena by MASTER Global Robotic Net. Such extreme Universe sources includes gamma-ray bursts, gravitational wave events, detected by LIGO/Virgo, fast radio bursts, high energy neutrino sources and others. Some of the neutrinos detected by ground-based facilities owe their births to supermassive black holes – blazars, which are in a special anxious state with high statistical reliability. We discovered the effect of a rapid decrease in the brightness of the blazar PKS 0735+17 at the time of the multiple detection of the high-energy neutrino event IceCube-211208A. This decrease in brightness within several hours was detected with a high confidence (SNR 10) in comparison with a multi-day brightening state of the blazar, which was accompanied not only by a maximum increase in the average brightness, but also by an increase in the amplitude of its brightness fluctuations. Additionally, we analyzed all cases of successful observation of blazars around neutrino events and obtained statistically reliable indications of the relationship between neutrino events and optical activity of blazars in the doubled error box at the 4.2 level. [ABSTRACT FROM AUTHOR]

This paper considers latest highlights in simultaneous and follow-up optical observations of high energy astrophysical phenomena by MASTER Global Robotic Net. Such extreme Universe sources includes gamma-ray bursts, gravitational wave events, detected by LIGO/Virgo, fast radio bursts, high energy neutrino sources and others. Some of the neutrinos detected by ground-based facilities owe their births to supermassive black holes – blazars, which are in a special anxious state with high statistical reliability. We discovered the effect of a rapid decrease in the brightness of the blazar PKS 0735+17 at the time of the multiple detection of the high-energy neutrino event IceCube-211208A. This decrease in brightness within several hours was detected with a high confidence (SNR 10) in comparison with a multi-day brightening state of the blazar, which was accompanied not only by a maximum increase in the average brightness, but also by an increase in the amplitude of its brightness fluctuations. Additionally, we analyzed all cases of successful observation of blazars around neutrino events and obtained statistically reliable indications of the relationship between neutrino events and optical activity of blazars in the doubled error box at the 4.2 level. [ABSTRACT FROM AUTHOR]

We present the results of the participation of the MASTER Global Robotic Network in the program to support the aLIGO (O1) and LIGO/Virgo (O2 and O3) gravitational-wave experiments in the electromagnetic channel. This study covers the first observing run O1 from September 2015 to January 2016, the second observing run O2 from November 2016 to August 2017 (only LIGO in January–July, joint LIGO/VIRGO (LVC) in August) and the third observing run O3 from April 2019 to April 2020. The main goal of these observations was to, for the first time in the history of astronomy, perform precise localization of gravitational-wave sources, which successfully resulted in the independent discovery of the kilonova using MASTER telescopes in the process of searching for the source of the GW170817 event. In many other events, dozens of optical transients unrelated to gravitational waves have been detected. Nevertheless, the experience of optical localization of gravitational waves is of exceptional importance for the development of a future successful strategy for the localization of gravitational wave events involving relativistic stars. In addition, objects detected in the analysis of huge areas in the sky, determined by the localization errors of the GW source, have been studied in particular detail by telescopes around the world. Objects such as supernovae, novae, active galactic nuclei, dwarf novae and other explosive phenomena in the Universe have been found and analyzed. More than 220 000 deg2 within the region of the most probable localization of a gravitational wave source have been explored by the MASTER Global Robotic Network. This paper reports on the observations of the MA-STER Global Robotic Network for all alert events from the O1, O2, and O3 observing runs. [ABSTRACT FROM AUTHOR]

We report on MASTER optical observations of an afterglow-like optical and X-ray transient AT2021lfa/ZTF21aayokph. We detected the initial steady brightening of the transient at 7σ confidence level. This allowed us to use smooth optical self-similar emission of GRBs model to constrain the explosion time to better than 14 min as well as to estimate its initial Lorentz factor Γ0 = 20 ± 10. Taking into consideration the low Γ0 and non-detection in gamma-rays, we classify this transient as the first failed GRB afterglow. [ABSTRACT FROM AUTHOR]

We report on the earliest detection of the optical transient MASTER OT J123248.62-012924.5 coincident within the error box with the optical and X-ray transient AT2021lfa/ZTF21aayokph. In our images the brightness of the object rises monotonically with confidence. We interpret this transient as a gamma-ray burst (GRB) characterized by smooth optical self-similar (SOSS) emission, while the nondetection of gamma-ray emission at space observatories is interpreted in terms of the hypothesis of a "failed" GRB. Thus, this is the first detection of a nonmonotonic orphan burst. [ABSTRACT FROM AUTHOR]

We present the results of early observations for 130 error-boxes of gamma-ray bursts performed with the Mobile Astronomical System of TElescope-Robots (MASTER) global network of robotic telescopes from Moscow State University in fully automatic mode (2011–2017). Among them, GRB 130907A, GRB 120811C, GRB 110801A, GRB 120404A, GRB 140129B, GRB140311B, and GRB 160227A are considered in details. Among these 130 gamma-ray bursts, in the first 60 s after the trigger with the Swift, Fermi, INTEGRAL, MAXI, Lomonosov, and Konus-Wind orbital observatories, the MASTER was pointed on 51 gamma-ray bursts, being the leader in terms of the first pointing. Full observation automation and MASTER own real-time image processing software allowed us to obtain unique data on early optical emission that accompanied 44 gamma-ray bursts (GRB 110801A, GRB120106A, GRB 120404A, GRB 120811C, GRB 120907A, GRB 121011A, GRB 130122A, GRB 130907A, GRB 131030A, GRB 131125A, GRB 140103A, GRB 140108A, GRB 140129B, GRB 140206A, GRB 140304A, GRB 140311B, GRB 140512A, GRB 140629A, GRB 140801A, GRB140907A, GRB 140930B, GRB141028A, GRB 141225A, GRB 150210A, GRB 150211A, GRB 150301B, GRB 150323C, GRB 150404A/Fermi trigger 449861706, GRB 150403A, GRB 150413A, GRB 150518A, GRB 150627A, GRB 151021A, GRB 151215A, GRB 160104A, GRB 160117B, GRB 160131A, GRB 160227A, GRB 160425A, GRB 160611A, GRB 160625B, GRB 160804A, GRB 160910A, GRB 161017A, GRB 161117A, GRB 161119A). We obtain light curves for 13 gamma-ray bursts among the above listed ones and compare the data in the optical (MASTER), X-ray (Swift-XRT), and hard X-ray (Swift-BAT) ranges. [ABSTRACT FROM AUTHOR]

The results of white-light photometry for a uniquely long series of data (13.5 hours of observations, 1124 measurements) for the Near-Earth Asteroid (NEA) 2015 TB145 are presented. These data were obtained with the MASTER-Amur and MASTER-Tavrida wide-field robotic telescopes of the Mobile Astronomical System of Telescope-Robots (MASTER) global network of Lomonosov Moscow State University, located in the Crimea and in Blagoveshchensk. The object moved by more than 120° during the observations. The asteroid passed the point of closest approach to the Earth, i.e., observations were carried during both the asteroid's approach and recession. Thus, due to the geometry of the passage, this series of observations contains information about the asteroid viewed at different angles, and is very suitable for precisely determining the shape of the object. Mathematical modeling of the light curve and astrometric positions (with the Asteroids3D code) was carried out, and the probable shape of the asteroid (conical) and the rotation period of 5.9 hours were obtained, as well as the orientation of the rotation axis in ecliptic coordinates: longitude λ = 53°, latitude β = −20°. The derived period coincides with twice the period of 2.9 hours obtained by other observers published earlier, within the uncertainties. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We report the discovery of a new eclipsing polar, MASTER OT J061451.70–272535.5, detected as an optical transient by MASTER auto-detection software at the recently commissioned MASTER-SAAO telescope. Time resolved (10–20 s) photometry with the SAAO 1.9-m and 1.0-m telescopes, utilizing the SHOC EM-CCD cameras, revealed that the source eclipses, with a period of 2.08 h (7482.9 |$\pm 3.5\,$| s). The eclipse light curve has a peculiar morphology, comprising an initial dip, where the source brightness drops to 50 per cent of the pre-eclipse level before gradually increasing again in brightness. A second rapid ingress follows, where the brightness drops by 60–80 per cent, followed by a more gradual decrease to zero flux. We interpret the eclipse profile as the result of an initial obscuration of the accretion hot-spot on the magnetic white dwarf by the accretion stream, followed by an eclipse of both the hotspot and partially illuminated stream by the red dwarf donor star. This is similar to what has been observed in other eclipsing polars such as HU Aqr, but here the stream absorption is more pronounced. The object was subsequently observed with South African Large Telescope (SALT) using the Robert Stobie Spectrograph (RSS). This revealed a spectrum with all of the Balmer lines in emission, a strong He  ii 4686 Å line with a peak flux greater than that of H β, as well as weaker He  i lines. The spectral features, along with the structure of the light curve, suggest MASTER OT J061451.70–272535.5 is a new magnetic cataclysmic variable, most likely of the synchronized Polar subclass. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We report the discovery and multicolour (VRIW) photometry of the rare explosive star MASTEROT J004207.99+405501.1 - a luminous red nova - in theAndromeda galaxy M31N2015-01a. We use our original light curve acquired with identical MASTER Global Robotic Net telescopes in one photometric system: VRI during the first 30 d and W (unfiltered) during 70 d. Also, we added published multicolour photometry data to estimate the mass and energy of the ejected shell and we discuss the likely formation scenarios of outbursts of this type. We propose an interpretation of the explosion that is consistent with an evolutionary scenario where the merging of stellar components or the disruption of the common envelope of a close binary can explain some luminous red novae. Radiative hydrodynamic simulations of a luminous red nova were carried out in extended parameter space to fit its light curves. We find that the multicolour passband light curves of the luminous red nova are consistent with an initial common envelope radius of 10 R⊙, a merger mass of 3M⊙ and an explosion energy of 3 × 1048 erg. As a result, the phenomenon of novae consists of two classes: classical nuclear novae and more rare events (red novae) connected with the loss of compact common envelopes. [ABSTRACT FROM AUTHOR]

The Advanced LIGO observatory recently reported the first direct detection of the gravitational waves (GWs) predicted by Einstein & Sitzungsber. We report on the first optical observations of the GW source GW150914 error region with the Global MASTER Robotic Net. Between the optical telescopes of electromagnetic support, the covered area is dominated by MASTER with an unfiltered magnitude up to 19.9 mag (5σ). We detected several optical transients, which proved to be unconnected with the GW event. The main input to investigate the final error box of GW150914 was made by the MASTER-SAAO robotic telescope, which covered 70 per cent of the final GW error box and 90 per cent of the common localization area of the LIGO and Fermi events. Our result is consistent with the conclusion (Abbott et al. 2016a) that GWs from GW150914 were produced in a binary black hole merger. At the same time, we cannot exclude that MASTER OT J040938.68-541316.9 exploded on 2015 September 14. [ABSTRACT FROM AUTHOR]

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., 1997b) 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. [ABSTRACT FROM AUTHOR]

We report early optical linear polarization observations of two gamma-ray burstsmade with the MASTER robotic telescope network. We found the minimum polarization for GRB 150301B to be 8 per cent at the beginning of the initial stage, whereas we detected no polarization for GRB 150413A 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 gammaray bursts during the non-monotonic stage of their evolution. We report that our team has discovered the optical counterpart of one of the bursts, GRB 150413A. [ABSTRACT FROM AUTHOR]

We report the early discovery of the optical afterglow of gamma-ray burst (GRB) 140801A in the 137 deg2 3-σ error-box of the Fermi Gamma-ray Burst Monitor (GBM). MASTER is the only observatory that automatically reacts to all Fermi alerts. GRB 140801A is one of the few GRBs whose optical counterpart was discovered solely from its GBM localization. The optical afterglow of GRB 140801A was found by MASTER Global Robotic Net 53 s after receiving the alert, making it the fastest optical detection of a GRB from a GBM error-box. Spectroscopy obtained with the 10.4-m Gran Telescopio Canarias and the 6-m Big Telescope Alt-azimuth of the Special Astrophysical Observatory of the Russian Academy of Sciences reveals a redshift of z = 1.32. We performed optical and near-infrared photometry of GRB 140801A using different telescopes with apertures ranging from 0.4 to 10.4 m. GRB 140801A is a typical burst in many ways. The rest-frame bolometric isotropic energy release and peak energy of the burst are Eiso = 5.54+0.26-0.24 × 1052 erg and Ep, rest ≃280 keV, respectively, which is consistent with the Amati relation. The absence of a jet break in the optical light curve provides a lower limit on the half-opening angle of the jet θ = 6°.1. The observed Epeak is consistent with the limit derived from the Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis show that GRB 140801A could belong to the class of intermediate duration. The rapid detection of the optical counterpart of GRB 140801A is especially important regarding the upcoming experiments with large coordinate error-box areas. [ABSTRACT FROM AUTHOR]

The main stages in the creation of the Russian segment of the MASTER network of robotic telescopes is described. This network is designed for studies of the prompt optical emission of gammaray bursts (GRBs; optical emission synchronous with the gamma-ray radiation) and surveys of the sky aimed at discovering uncataloged objects and photometric studies for various programs. The first results obtained by the network, during its construction and immediately after its completion in December 2010, are presented. Eighty-nine alert pointings at GRBs (in most cases, being the first ground telescopes to point at the GRBs) were made from September 2006 through July 2011. The MASTER network holds first place in the world in terms of the total number of first pointings, and currently more than half of first pointings at GRBs by ground telescopes are made by the MASTER network. Photometric light curves of GRB 091020, GRB 091127, GRB 100901A, GRB 100906A, GRB 10925A, GRB 110106A, GRB 110422A, and GRB 110530A are presented. It is especially important that prompt emission was observed for GRB 100901A and GRB 100906A, and thar GRB 091127, GRB 110422A, and GRB 110106A were observed from the first seconds in two polarizations. Very-wide-field cameras carried out synchronous observations of the prompt emission of GRB 081102, GRB 081130B, GRB 090305B, GRB 090320B, GRB 090328, and GRB 090424. Discoveries of Type Ia supernovae are ongoing (among them the brightest supernova in 2009): 2008gy, 2009nr, 2010V, and others. In all, photometry of 387 supernovae has been carried out, 43 of which were either discovered or first observed with MASTER telescopes; more than half of these are Type Ia supernovae. Photometric studies of the open clusters NGC 7129 and NGC 7142 have been conducted, leading to the discovery of 38 variable stars. Sixty-nine optical transients have been discovered. [ABSTRACT FROM AUTHOR]

ABSTRACT We present the results of the prompt, early and afterglow optical observations of five γ-ray bursts (GRBs): GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A. These observations were made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II Net), the 1.5-m telescope of the 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 the cessation of γ-ray emission, at 113 and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted in two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. A more detailed analysis of GRB 100901A and GRB 100906A, supplemented by Swift data, provides the following results and indicates different origins for the prompt optical radiation in the two bursts. The light-curve patterns and spectral distributions suggest that there is a common production site for the prompt optical and high-energy emission in GRB 100901A. The results of the spectral fits for GRB 100901A in the range from optical to X-ray favour power-law energy distributions and a consistent value 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. We obtain an upper limit on the value of the optical extinction on the host of GRB 100906A. [ABSTRACT FROM AUTHOR]