GCN Circular 20402

V.V.Bogomolov, S.I.Svertilov,
A.M.Amelushkin, V.O.Barinova, M.I.Panasyuk, A.V.Bogomolov, A.F.Iyudin,
V.V.Kalegaev, D.Nguen,  V.L. Petrov, I.V.Yashin, P.S.Kazarian, 
N.L.Dzhioeva,
Physics Department, Skobel`tsyn Institute of Nuclear Physics, Lomonosov
Moscow State University

V. Lipunov, E.S. Gorbovskoy, N.Tyurina, D.Kuvshinov, M.Panchenko
Lomonosov Moscow State University, Sternberg Astronomical Institute

I. Park, J. Lee, S. Jeong
Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu, 
Suwonsi,
Korea

At event time for G268556 the detectors BDRG-1 and BDRG-2 on-board 
Lomonosov were directed  >60 degrees far from all regions present on LIGO 
probability map for G268556. BDRG-3 detector observed the southern high 
probability region directed to RA=25.8, Dec=-30.7. The Lomonosov satellite 
was located over South Africa at outer regions of SAA leading to high 
background. No burst-like events were observed, the 3 sigma upper limit 
for 1s-long GRB flux in 20-800 keV range is 2.5 cm-2*s-1.
The time intervals when the region of maximal probability of GW source was 
in BDRG FOV on 04.01.2017 from 9h to 13h are   9:07-9:27, 9:33-9:47, 
10:42-11:02, 11:07-11:24, 12:17-12:37, 12:42-12:59. No on-board 
GRB-triggers were generated at this time intervals.
BDRG on-board triggers were generated 4 times during the time period from 
10 hours before GW event to 10 hours after it  (at 02:33:17, 0 4:12:19, 
08:06:49 and 13:36:41).The significance of all these triggers do not 
exceed 9.5 sigma correspondent to the level of random events occurring ~10 
times per day. The  upper limit for 1s-GRB flux in 50-300 keV is 0.5 
cm-2*s-1 equivalent to 1e-7 erg/cm2 for typical GRB spectra.

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