[vsnet-grb-info 15097] Konus-Wind observation of GRB 140611A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16389
SUBJECT: Konus-Wind observation of GRB 140611A
DATE:    14/06/12 11:53:32 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, A. Tsvetkova, A. Lyssenko, and T. Cline
on behalf of the Konus-Wind team, report:

The short/hard GRB 140611A (IPN triangulation: Golenetskii at al., GCN 16384;
Swift-BAT detection in ground analysis: Cummings, GCN 16386)
triggered Konus-Wind at T0=13864.927 s UT (03:51:04.927).

The burst light curve starts, at ~T0-0.1, with a rise of short,
bright pulse with a duration of ~0.5 s, followed by a weaker,
second pulse from ~T0-1.5 s to ~T0+2.2 s.
The total duration of the burst is ~2.3 s.
The emission is seen up to ~5 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.5(-0.3,+0.4)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.256 s,
of 4.5(-0.5,+0.5)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 18 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -0.68 (-0.18,+0.22),
and the peak energy Ep = 1460(-360,+520) keV,
chi2 = 111/98 dof.
Fitting this spectrum with the Band model yields the same
values of alpha and Ep with an upper limit on beta of -2.3.

The spectrum near the maximum count rate
(measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 5 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -0.24(-0.14,+0.16),
and the peak energy Ep = 1410(-160,+170) keV,
chi2 = 69/68 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB140611_T13864/

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