Wide-Field Gamma-Spectrometer BDRG: GRB Monitor On-Board the Lomonosov Mission

Abstract

The study of GRB prompt emissions (PE) is one of the main goals of the Lomonosov space mission. The payloads of the GRB monitor (BDRG) with the widefield optical cameras (SHOK) and the ultra-fast flash observatory (UFFO) onboard the Lomonosov satellite are intended for the observation of GRBs, and in particular, their prompt emissions. The BDRG gamma-ray spectrometer is designed to obtain the temporal and spectral information of GRBs in the energy range of 10-3000 keV as well as to provide GRB triggers on several time scales (10 ms, 1 s and 20 s) for ground and space telescopes, including the UFFO and SHOK. The BDRG instrument consists of three identical detector boxes with axes shifted by 90 • from each other. This configuration allows us to localize a GRB source in the sky with an accuracy of ∼ 2 • .Each BDRG box contains a phoswich NaI(Tl)/CsI(Tl) scintillator detector. A thick CsI(Tl) crystal in size of ∅130 × 17 mm is placed underneath the NaI(Tl) as an active shield in the soft energy range and as the main detector in the hard energy range. The ratio of the CsI(Tl) to NaI(Tl) event rates at varying energies can be employed as an independent metric to distinguish legitimate GRB signals from false positives originating from electrons in near-Earth vicinities.The data from three detectors are collected in a BA BDRG information unit, which generates a GRB trigger and a set of data frames in output format. The scientific data output is ∼ 500 Mb per day, including ∼ 180 Mb of continuous data for events with durations in excess of 100 ms for 16 channels in each detector, detailed energy spectra, and sets of frames with ∼ 5 Mb of detailed information for each burst-like event. A number of pre-flight tests including those for the trigger algorithm and calibration were carried out to confirm the reliability of the BDRG for operation in space.

Universat-SOCRAT multi-satellite project to study TLEs and TGFs

“…The GFM instrument should provide the monitor type observations of the upper atmosphere in the hard X-rays and soft gamma-rays, in an energy range of 0.01-3.0 MeV, with the possibility of rough localization of the TGF source. GFM will consist of three identical detector units, which are similar to the detector unit used as gammaray burst monitor of the Lomonosov mission (Svertilov et al 2018). This detector is also the successor of detectors that successfully registered TGF on the Vernov satellite (Bogomolov et al (2017)).…”

Observations of Near-Earth Optical Transients with the Lomonosov Space Observatory

“…The BDRG [5] and UBAT (UFFO Burst Alert Telescope) [6] devices are based on di erent princi-ff ples for the detection of hard X-ray emission onboard the Lomonosov spacecraft. Each is able to record GRBs and transmit the corresponding signals to the MASTER-SHOK devices in real time.…”

“…Each is able to record GRBs and transmit the corresponding signals to the MASTER-SHOK devices in real time. The BDRG [5]consists of three identical NaI(Tl)/CsI(Tl) scintillator detector units directed toward di erent sectors of ff the sky, which are able to determine the position of a new source on the sky from the di erences between ff the count rates of each of the detectors. The UBAT [6] is part of the Ultra-Fast Flash Observatory (UFFO) onboard the Lomonosov; this is an X-ray telescope with a coded mask.…”

“…4) includes eight observatories: MASTER-Amur, MASTER-Tunka, MASTER-Ural, MAS-TER-Kislovodsk, MASTER-Tavrida (Russian Fed-eration), MASTER-SAAO (South Africa), MAS-TER-IAC (Spain, Canarias), and MASTER-OAFA (Argentina) [4]. Each of these observatories is able to survey 128 deg 2 /hour with a limiting magnitude of 20 m on dark, moonless nights, and each is equipped with two wideangle optical telescopes with a total field of view of 8 deg 2 , a 4098 × 4098 pixel CCD camera with a scale of 1.85 /pixel, and a photometer with Johnson BVRI filters and polarizers [5,16]. All alerts from onboard the Lomonosov Space Observatory are transmitted to the Earth through the Globalstar channels with a minimum time delay, making it possible for any telescope in the world to observe a GRB registered by the Lomonosov mis-sion.…”

Detection of Low-Energy X-rays Using YSO Scintillation Crystal Arrays for GRB Experiments

“…The Fermi gamma-ray telescope [10], launched in 2008 with an unrivaled spectral range, provides new data on gamma-ray emissions from GRBs. Other space missions for the observation of GRBs are INTEGRAL [11], AGILE [12], Suzaku [13], MAXI/ISS [14], the Interplanetary Network (IPN) [15,16] satellites, and the recent but short-lived BDRG/Lomonosov [17] and UFFO/Lomonosov [18].…”