GCN Circular 12701

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

The long intense GRB 111215B
(localized by IPN: Hurley et al., GCN 12698
Not found
 
 
)
triggered Konus-Wind at T0=72682.720s UT (20:28:02.720)

The light curve shows multiple partly overlapping pulses
with the brightest peak at ~T0+12s.
A total duration of the burst is ~75 s.
The emission is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB111215_T73682/

As observed by Konus-Wind the burst
had a fluence of 5.3(-1.1,+1.1)x10-5 erg/cm2,
and a 256-ms peak flux, measured from T0+11.776 s,
of 6.1(-0.6,+0.6)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+72.192 s)
is best fitted in the 20 keV - 10 MeV range
with the GRB (Band) model, for which:
the low-energy photon index alpha = -1.18 (-0.12, +0.18),
the high energy photon index beta = -2.3 (-0.6, +0.2),
the peak energy Ep = 250(-60, +65) keV,
chi2 = 88.2/88 dof.

The spectrum at the maximum count rate
(measured from T0+7.680 to T0+14.848 s)
is best fitted in the 20 keV - 10 MeV range
by a power law with exponential cutoff model, for which
alpha = -1.03 (-0.10, +0.11),
and Ep = 413(-57, +75) keV,
chi2 = 101.9/89 dof.
Fitting this spectrum by the GRB (Band) function yields
the same alpha and Ep with a high energy photon index
beta < -2.6 (chi2 = 101.9/88 dof).

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