GCN Circular 18636

S. Golenetskii, R. Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team, report:

The long-duration GRB 151120A
(INTEGRAL ISGRI detection: S. Mereghetti et al., GCN Circ. 18623
Not found
 
 
;
Fermi GBM detection: A. von Kienlin, GCN Circ. 18628
Not found
 
 
)
triggered Konus-Wind at T0=30171.357 s UT (08:22:51.357).

The burst light curve shows a multipeaked structure
started at ~T0-1.3 s with a total duration of ~20 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB151120_T30171/

As observed by Konus-Wind, the burst
had a fluence of 7.20(-1.25,+1.79)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.752 s,
of 2.09(-0.88,+1.15)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+24.832 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.26 (-0.48,+0.77),
the high energy photon index beta = -2.70 (-0.88,+0.35),
the peak energy 106 (-19,+20) keV
(chi2 = 84/85 dof)

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = 0.81 (-0.75,+3.91),
the high energy photon index beta = -2.42 (-0.38,+0.35),
the peak energy 113 (-40,+22) keV
(chi2 = 81/82 dof)

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.