GRB 151107B

A. Yoshida, T. Sakamoto, I. Takahashi, Y. Kawakubo, K. Senuma, 
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), 
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), 
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) 
and the CALET collaboration:

The long-duration GRB 151107B (Stanbro et al. GCN Circ. 18570
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 ) triggered the CALET 
Gamma-Ray Burst Monitor (CGBM) at 20:24:54.77 UT on 7 November 2015.  The burst 
was detected by all three CGBM instruments.  Based on the signal-to-noise among the 
instruments, the incident angle of the burst was estimated as ~40-70 deg from the zenith 
direction of CGBM.  This estimated incident angle is roughly consistent with the IPN 
triangulation (Hurley et al., GCN Circ. 18577
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 ).

The light curve of the Soft Gamma-ray Monitor (SGM; 30 keV - 20 MeV) shows the main 
peak starting from T0-5 sec, peaking at T0+5 sec and ending at T0+~30 sec.  The 
second weak peak starts from T0+90 sec, peaks at T0+95 sec and ends at T0+100 sec.  
The T90 duration measured by the SGM data is 95.0 +- 1.4 s (40-920 keV).  

Currently, CALET is in the commissioning phase.  Further information about CALET and 
CGBM can be found at http://calet.jp/en/ and http://www.en.yoshida-agu.net/research/calet-gbm

K. Hurley, on behalf of the IPN,

S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks, 
D. Svinkin, and T. Cline, on behalf of the Konus-Wind team,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on
behalf of the GRS-Odyssey GRB team,

report:

GRB 151107B (Stanbro and Meegan, GCN 18570
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 ) was also observed by Konus-Wind
and Mars Odyssey-HEND.  We have triangulated it to a preliminary annulus centered
at RA, Dec(2000) = 357.447, -2.630, whose radius is 55.156 +/- 0.054 degrees
(3 sigma).  The minimum distance between the center line of this annulus 
and the MASTER-NET optical transient (Lipunov et al., GCN 18576
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 ) is 3.22
degrees, supporting the conclusion that the OT and the GRB are indeed unrelated.
A map has been posted at ssl.berkeley.edu/ipn3/151107B.

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.


The message may be cited.

S.Karpov, G.Beskin (SAO RAS and Kazan Federal University, Russia), S.Bondar,
E.Ivanov, E.Katkova, A.Perkov, N.Orekhova (OJS RPC PSI, Russia), A.Biryukov
(SAI MSU and Kazan Federal University, Russia), V.Sasyuk (Kazan Federal
University, Russia)

The localization of Fermi GBM trigger 468620696 / GRB 151107B (Stanbro et al,
GCN Circ. 18570
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 ) has been observed by Mini-MegaTORTORA nine-channel wide-field
monitoring system (located at Special Astrophysical Observatory near Russian
6-m telescope and belonging to Kazan Federal University) before, during and
after the trigger time at 2015-11-07 20:24:52.30 UT. The whole final 1-sigma
localization box (as well as 6 more degrees around it) has been covered since
20:19:23 UT (T-329.3 s) and until 20:25:18 UT (T+25.7 s, thus covering the
brightest part of first gamma-ray peak) with temporal resolution of 0.1 s in
white light. Dedicated real-time transient detection pipeline did not detect
any events longer than 0.3 s and brighter than approximately V=10.5 mag. Visual
inspection of co-added images with 10 s effective exposure (summation of 100
consecutive frames each) has not revealed any variable source down to V=12.0
mag during that interval.

At 20:25:18 UT the system initiated a repointing following the initially
distributed GBM coordinates, and since 20:25:55 UT (T+62.7 s, during the
continuing gamma-ray activity) till 20:35:59 UT (T+666.7 s) acquired 20x9 deep
images with 30 s exposures in white light in a 30x30 degree field of view
centered on RA=24.1 Dec=44.8. The whole final 1-sigma localization was still
inside the field of view. Quick-look analysis of the acquired data has not
revealed any variable object down to roughly V=13.5 mag over that time interval.

The analysis is ongoing.

Matthew Stanbro (UAH) and Charles Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 20:24:52.30 UT on 07 November 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151107B (trigger 468620696 / 151107851).

The on-ground calculated location, using the GBM trigger
data, is RA = 31.3, DEC = 45.6, with an uncertainty
of 1.7 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 40 degrees.

The GBM light curve consists of 2 separate episodes
with a duration (T90) of about 139 s (50-300 keV).
The time-averaged spectrum from T0+2 s to T0+137 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.20 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 347 +/- 25 keV

The event fluence (10-1000 keV) in this time interval is
(3.11 +/- 0.07)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.13 s in the 10-1000 keV band
is 10.9 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

-- 
Matthew C. Stanbro
Fermi GBM Graduate Research Assistant
University of Alabama in Huntsville