Prompt, early, and afterglow optical observations of five gamma-ray bursts (GRBs 100901A, 100902A, 100905A, 100906A, and 101020A)

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.Comment: 18 pages, 14 figures, 14 tables, 5 machine readable tables; accepted for publication in MNRA

The HiSCORE Project

A central question of Astroparticle Physics, the origin of cosmic rays, still remains unsolved. HiSCORE (Hundred*i Square-km Cosmic ORigin Explorer) is a concept for a large-area wide-angle non-imaging air shower detector, addressing this question by searching for cosmic ray pevatrons in the energy range from 10TeV to few PeV and cosmic rays in the energy range above 100TeV. In the framework of the Tunka-HiSCORE project, first prototypes have been deployed on the site of the Tunka-133 experiment, where we plan to install an engineering array covering an area of the order of 1km2. On the same site, also imaging and particle detectors are planned, potentially allowing a future hybrid detector system. Here we present the HiSCORE detector principle, its potential for cosmic ray origin search and the status of ongoing activities in the framework of the Tunka-HiSCORE experiment

Ранние оптические наблюдения семи гамма-всплесков в сравнении с их гамма-рентгеновскими характеристиками на глобальной сети телескопов-роботов МГУ МАСТЕР

Seven gamma-ray bursts – GRB 130907A, GRB 140311B, GRB 140129B, GRB 160227A, GRB 120404A, GRB 110801A, and GRB 120811C were observed by the MSU MASTER (Mobile Astronomical System of TElescope Robots) Global Network. Full automation of the observations provided for obtaining unique data on the properties of early optical radiation accompanying gamma-ray bursts. The data are compared in the optical (MASTER), X-ray (SWIFT X-ray Telescope, XRT) and gamma (SWIFT Burst Alert Telescope, BAT) ranges. Based on the data obtained, two groups are identified, and their radiation mechanisms are revealed. The effect of gamma-ray bursts on the biosphere of the Earth is determined, and the estimates and the scale of such an effect are considered.В статье представлены результаты наблюдений семи гамма-всплесков – GRB 130907A, GRB 140311B, GRB 140129B, GRB 160227A, GRB 120404A, GRB 110801A, GRB 120811C, полученные на телескопах-роботах глобальной сети МГУ «МАСТЕР». Полная автоматизация наблюдений позволила получить уникальные данные о свойствах раннего оптического излучения, сопровождавшего гамма-всплески. Выполнено сравнение данных в оптическом (МАСТЕР), рентгеновском (SWIFTX-rayTelescope (XRT)) и гамма (SWIFTBurstAlertTelescope (BAT)) диапазонах. На основании полученных данных выделены две группы, для которых определен механизм излучения. Также определено воздействие гамма-всплесков на биосферу Земли и рассмотрены оценки и масштаб такого влияния

The HiSCORE experiment and its potential for gamma-ray astronomy

The HiSCORE (Hundred*i Square-km Cosmic ORigin Explorer) detector aims at the exploration of the accelerator sky, using indirect air-shower observations of cosmic rays from 100 TeV to 1 EeV and gamma rays in the last remaining observation window of gamma-ray astronomy from 10 TeV to several PeV. The main questions addressed by HiSCORE are cosmic ray composition and spectral measurements in the Galactic/extragalactic transition range, and the origin of cosmic rays via the search for gamma rays from Galactic PeV accelerators, the pevatrons. HiSCORE is based on non-imaging Cherenkov light-front sampling with sensitive large-area detector modules of the order of 0.5 m2. A prototype station was deployed on the Tunka cosmic ray experiment site in Siberia, where an engineering array of up to 1km2 is planned for deployment in 2012/2013. Here, we address the expected physics potential of HiSCORE, the status of the project, and further plans.M. Tluczykont... G. P. Rowell... et al

Hardware and first results of TUNKA-HiSCORE

As a non-imaging wide-angle Cherenkov air shower detector array with an area of up to 100 km2, the HiSCORE (Hundred?i Square km Cosmic ORigin Explorer) detector concept allows measurements of gamma rays and cosmic rays in an energy range of 10 TeV up to 1 EeV. In the framework of the Tunka-HiSCORE project we have started measurements with a small prototype array, and planned to build an engineering array (1 km2) on the site of the Tunka experiment in Siberia. The first results and the most important hardware components are presented here. © 2013 Elsevier B.V.M. Kunnas … G.P. Rowell … et al

Amplitude calibration with the HiSCORE-9 array

HiSCORE is a non-imaging wide-angle Cherenkov array for the detection of extensive air showers induced by ultrahigh energy gamma-rays above 10 TeV and cosmic ray studies above 100 TeV. In October 2013 a 9-station engineering array has been deployed in Tunka valley. For HiSCORE-9, two DAQ systems are being used. The second system is a DRS4 based acquisition system with WhiteRabbit integrated time synchronization. We present the first results on the amplitude calibration from the data of this DAQ system.Peer Reviewe