GCN Circular 18576

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

E. Gorbovskoy, V. Lipunov, V.Shumkov, N.Tyurina, V.Kornilov, P.Balanutsa, 
A.Kuznetsov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institute

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik
Kislovodsk Solar Station of the Pulkovo Observatory

O.Gress, K.Ivanov, N.M.Budnev, V.A.Poleshchuk
Irkutsk State University

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

V.Krushinski, I.Zalozhnih
Ural Federal University, Kourovka

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)

MASTER II  robotic telescope (MASTER-Net http://observ.pereplet.ru) 
located in IAC (Tenerife, Spain) was pointed to the FERMI GBM GRB151107B 
14 sec after notice time and 
60 sec after trigger time at 2015-11-07 20:25:52 UT. Our first (10s 
exposure)  set  limit is 16.8 within FERMI 
error-box (ra=00 42 28 dec=+48 48 58 r=4.5, Stanbro and Meegan, GCN 18570
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 ).

MASTER II  robotic telescope  located in Kislovodsk was pointed to the 
GRB151107B 21 sec after notice time and 66 sec after trigger time at 
2015-11-07 20:25:59 UT. Our first (10s exposure)  set limit is  18.1 
within FERMI error-box . The summary (60sec) unfiltered optical limit is 
19.5m.

MASTER II  robotic telescope located in SAAO (South Africa, Sutherland) 
was pointed to the  GRB151107B 20 sec after notice time and 66 sec after 
trigger time at 2015-11-07 20:25:58 UT. Our first (10s exposure)
set limit is 15.4.

There are prompt pointing observations because duration of the GRB is ~140 
s (Stanbro and Meegan, GCN 18570
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 )

After 5 minutes of alert observations of the center of error box, 
telescopes in IAC and Kislovodsk started the inspect survey inside large 
Fermi error box (ra=00 42 28 dec=+48 48 58 r=4.533300)  obtained by GCN 
socket.

As a result, we cover more than 98% of 1 sigma+systematic  and 85% of 
3-sigma + systematic of the FERMI GBM final error box (Stanbro et. al. 
GCN 18570
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 ) with upper limit up to 19 mag during this night.
The coverage map is available here:

http://master.sai.msu.ru/static/GRB/GRB151107B.png

There is 1 possible OTs was found up to now  - 
MASTER OT J015539.85+485955.6   published yesterday 
(Shumkov et al., Atel #8262).
(RA, Dec) = 01h 55m 39.85s +48d 59m 55.6s

The OT mag is 15.2 on 2015-11-07.99775 UT. The 
specrtrum was done by follow up Liverpool Telescope
(La Palma) observations shows a broad continuum, consistent with
that expected from a dwarf nova in outburst ( Piascik & Steele, ATel #8265). 
The brightness is not sufficiantly changed after half of the day (during 
independently ASAS detection Holoin et al., ATEL #8260) and our today 
imaging (2015-11-10 17:16:26.513UT, m_OT=15.5+-0.1) shows that OT doesn't 
fade essntially with respect to discovery  magnitude contraverse to GRB 
optical afterglow .

The search is continuing.


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