[vsnet-grb-info 14216] Konus-Wind observation of GRB 131127B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15530
SUBJECT: Konus-Wind observation of GRB 131127B
DATE:    13/11/28 13:06:06 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

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

The bright, long-duration GRB 131127B
(Fermi GBM detection: von Kienlin, GCN 15528;
IPN triangulation: Golenetskii at al., GCN 15529)
triggered Konus-Wind at T0=51139.678 s UT (14:12:19.678).

The burst light curve shows multiple overlapped pulses
from ~T0-0.5 s to ~T0+20 s.
The emission is seen up to ~12 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB131127_T51139/

As observed by Konus-Wind, the burst
had a fluence of (4.1 ± 0.3)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+4.160 s,
of (1.15 ± 0.08)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+21.760 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.20 ± 0.11,
the high energy photon index beta = -2.51 ± 0.19,
the peak energy Ep = 165 ± 17 keV,
chi2 = 140/97 dof.

The spectrum near the maximum count rate
(measured from T0 to T0+5.376 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.92 ± 0.14,
the high energy photon index beta = -2.43 ± 0.19,
the peak energy Ep = 218 ± 27 keV,
chi2 = 128/97 dof.

All the quoted values are preliminary.