[vsnet-grb-info 14024] Konus-Wind observation of GRB 131014A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15338
SUBJECT: Konus-Wind observation of GRB 131014A
DATE:    13/10/15 07:56:52 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 long-duration very bright GRB 131014A
(Fermi GBM detection: Fitzpatrick & Xiong, GCN 15332;
Fermi LAT detection: Desiante et al., GCN 15333)
triggered Konus-Wind at T0=18541.405 s UT (05:09:01.405).

The light curve shows multiple bright, overlapped
pulses from ~T0 s to ~T0+6~s.
The emission at this phase of the event is seen up to ~12 MeV.
The burst was followed by a ~150s-long decaying tail of
a weak, soft, extended emission.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB131014_T18541/

As observed by Konus-Wind, the burst
had a fluence of (2.05 ± 0.03)x10-4 erg/cm2,
and a 64-ms peak flux, measured from T0+1.664 s,
of (2.10 ± 0.04)x10-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+12.288 s)
is best fit in the 50 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.79 ± 0.04,
the high energy photon index beta = -2.89 ± 0.08,
the peak energy Ep = 346 ± 9 keV,
chi2 = 118/94 dof.

The spectrum near the maximum count rate
(measured from T0+1.536 s to T0+1.792 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 = -0.42 ± 0.07,
the high energy photon index beta = -2.87 ± 0.13,
the peak energy Ep = 607 ± 25 keV,
chi2 = 77.5/77 dof.

All the quoted results are preliminary.