GCN Circular 16117

Subject

Konus-Wind observation of GRB 140416A

Event

Date

2014-04-18T14:46:57Z (12 years ago)

From

Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The long-duration, very intense GRB 140416A
(Fermi GBM detection: Jenke, GCN 16115Loading...
 
 ;
IPN triangulation: Hurley at al., GCN 16116Loading...
 
 )
triggered Konus-Wind at T0=5196.209 s UT (01:26:36.209).

The burst light curve shows multiple peaks from ~T0-24 s to ~T0+28 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/GRB140416_T05196/

As observed by Konus-Wind, the burst
had a fluence of 6.9(-0.1,+0.1)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+7.168 s,
of 1.5(-0.1,+0.1)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+32.768 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 = -1.43 (-0.06,+0.07),
the high energy photon index beta = -2.95 (-0.31,+0.18),
the peak energy Ep = 97 (-4,+4) keV,
chi2 = 88.4/96 dof.

The spectrum near the maximum count rate
(measured from T0+6.912 to T0+7.424 s)
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.78 (-0.14,+0.15),
the high energy photon index beta = -3.8 (-6.2,+0.6),
the peak energy Ep = 176 (-16,+18) keV,
chi2 = 81.5/90 dof.

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