E. A. Kuznetsova

Experiment on the Vernov satellite: Transient energetic processes in the Earth’s atmosphere and magnetosphere. Part I: Description of the experiment

The program of physical studies on the Vernov satellite launched on July 8, 2014 into a polar (640 × 830 km) solar-synchronous orbit with an inclination of 98.4° is presented. We described the complex of scientific equipment on this satellite in detail, including multidirectional gamma-ray detectors, electron spectrometers, red and ultra-violet detectors, and wave probes. The experiment on the Vernov satellite is mainly aimed at a comprehensive study of the processes of generation of transient phenomena in the optical and gamma-ray ranges in the Earth’s atmosphere (such as high-altitude breakdown on runaway relativistic electrons), the study of the action on the atmosphere of electrons precipitated from the radiation belts, and low- and high-frequency electromagnetic waves of both space and atmospheric origin.

Experiment on the Vernov satellite: Transient energetic processes in the Earth’s atmosphere and magnetosphere. Part II. First results

We present the first experimental results on the observation of optical transients, gamma-ray bursts, relativistic electrons, and electromagnetic waves obtained during the experiment with the RELEC complex of scientific equipment on the Vernov satellite.

Complete set of detectors for studying cosmic gamma-ray bursts onboard the Lomonosov satellite

The scientific instruments onboard the Lomonosov satellite include a complete set of detectors designed to study the gamma and optical emission of cosmic gamma-ray bursts (GRBs). The BDRG gamma spectrometer ensures producing a trigger of a GRB and studying GRB properties in the energy range of 10–3000 keV as well as determining the GRB source coordinates by comparing readings of three differently directed detectors. The SHOK optical cameras (with a field of view of ~20 × 40 degrees) fix a set of images by the GRB trigger preceding the trigger and a post-trigger set at a frequency of about five frames per second. The UFFO instrument incorporates the UBAT telescope with a coding mask for measurements within a range of hard X rays and soft gamma rays and the SMT optical slewing mirror telescope, which can be directed at the GRB source in about 1 s to measure the GRB optical emission at early stages.

Comparison cosmic ray irradiation simulation and particle beam test on UFFO Burst Alert & Trigger telescope(UBAT) detectors

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.

Cosmic ray effect on the X-ray Trigger Telescope of UFFO/Lomonosov using YSO scintillation crystal array in space

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 of UFFO-Pathfinder: first performance report 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.

Cosmic gamma-ray bursts detected in the RELEC experiment onboard the Vernov satellite

The RELEC scientific instrumentation onboard the Vernov spacecraft launched on July 8, 2014, included the DRGE gamma-ray and electron spectrometer. This instrument incorporates a set of scintillation phoswich detectors, including four identical X-ray and gamma-ray detectors in the energy range from 10 keV to 3 MeV with a total area of ~500 cm2 directed toward the nadir, and an electron spectrometer containing three mutually orthogonal detector units with a geometry factor of ~2 cm2 sr, which is also sensitive to X-rays and gamma-rays. The goal of the space experiment with the DRGE instrument was to investigate phenomena with fast temporal variability, in particular, terrestrial gammaray flashes (TGFs) and magnetospheric electron precipitations. However, the detectors of the DRGE instrument could record cosmic gamma-ray bursts (GRBs) and allowed one not only to perform a detailed analysis of the gamma-ray variability but also to compare the time profiles with the measurements made by other instruments of the RELEC scientific instrumentation (the detectors of optical and ultraviolet flashes, the radio-frequency and low-frequency analyzers of electromagnetic field parameters). We present the results of our observations of cosmicGRB 141011A and GRB 141104A, compare the parameters obtained in the GBM/Fermi and KONUS–Wind experiments, and estimate the redshifts and Eiso for the sources of these GRBs. The detectability of GRBs and good agreement between the independent estimates of their parameters obtained in various experiments are important factors of the successful operation of similar detectors onboard the Lomonosov spacecraft.