ИСТИНА

Different kinds of Transient Luminous Events (TLE) and Terrestrial Gamma Flashes (TGF) were observed during the Vernov mission from July,8 to December, 14 2014. The Vernov satellite was launched into a polar solar-synchronous orbit with small eccentricity 640x830 km and period about 98 min. Such orbit provides the favorable conditions for the Atmosphere study at different latitudes including as Equatorial as Polar Regions. The wide band observations of the Atmosphere from radio to gamma rays as well as detection of relativistic electrons and electromagnetic waves in the near-Earth space were realized in this experiment. The RELEC (Relativistic Electrons) complex of instruments on-board the Vernov spacecraft includes two identical X- and gamma-ray detectors of high temporal resolution and sensitivity (DRGE-1 & DRGE-2), three axis position detectors for high-energy electrons and protons (DRGE-3), UV TLE imager (MTEL), UV detector (DUV), low frequency analyser (LFA), radio frequency analyser (RFA), and electronics module responsible for control and data collection (BE). Study of fine time structure of transient atmospheric events in UV, X- and gamma rays is among the Vernov mission tasks. The main instrument for TGF observation is DRGE gamma-ray spectrometer providing time resolution (~15 microsec) measurements in the 10-3000 keV energy range with four detectors directed to atmosphere. Total area of DRGE detectors is ~500 cm2. The data were recorded both in monitoring and gamma by gamma modes. Events with 10-40 gammas in a burst with duration <1ms were detected. The TGF candidate database includes dozens of events among which a few ones were detected in Polar Regions far away from Thunderstorms. There is also no direct indication that those flashes were accompanied by radio pulses in low frequency (~0.1 – 4x10*4 Hz) and radio frequency (0.05-15 MHz) bands as well as by lightning from WWLN. Similar 10-3000 keV gamma-ray detectors are used in BDRG instrument on-board Lomonosov satellite launched to the polar ~500 km high orbit on 28.04.2016. The instrument was designed for cosmic GRB study but its characteristics allow one to provide the TGF search using fast on-board trigger (t=10ms) as well as the analysis of non-triggered data recorded in gamma-by-gamma mode. The first results of TGF search by BDRG/Lomonosov will be reported.