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GCN Circular 15870

Subject
Konus-Wind observation of exceptionally bright GRB 140219A
Date
2014-02-21T11:42:29Z (10 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@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, exceptionally bright and hard GRB 140219A (localized 
by IPN: Hurley et al., GCN 15864; GBM detection: Zhang, GCN 15866; LAT 
detection: Guiriec et al., GCN 15867) triggered Konus-Wind at 
T0=71162.611 s UT (19:46:02.611).

The burst light curve shows an extremely bright multi-peaked pulse with 
a duration of ~2.5 s followed by a less intense multi-peaked emission 
episodes until ~T0+26 s and a very weak tail until ~T0+35 s.
The emission is seen up to ~18 MeV.

As observed by Konus-Wind, the burst had a fluence of (1.14 � 
0.02)x10^-3 erg/cm2, and a 16-ms peak flux, measured from T0+0.240 s,
of (1.44 � 0.12)x10^-3 erg/cm2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+38.912 s)
is best fit (in the 26 keV - 18 MeV range)
by a GRB (Band) model with the following model parameters:
the low-energy photon index alpha = -1.07 � 0.01,
the high energy photon index beta = -3.26(-0.88,+0.38),
the peak energy Ep = 2777 � 70 keV,
chi2 = 112.7/96 dof.

The spectrum of the main pulse (measured from T0 to T0+2.304 s)
is best fit (in the 26 keV - 18 MeV range)
by a GRB (Band) model with the following model parameters:
the low-energy photon index alpha = -0.65 � 0.04,
the high energy photon index beta = -3.28(-0.89,+0.39),
the peak energy Ep = 3363 � 141 keV,
chi2 = 47.9/77 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB140219_T71162/

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

The derived peak flux and Epeak are the highest ever measured for GRBs 
with Konus-Wind during almost 20 years of its continuous observations:
the peak flux is ~50% higher than the previous record holder, GRB 
110918A, with the measured peak flux of ~0.9x10^-3 erg/cm2/s (Frederiks 
et al. ApJ, 779, 151 (2013)).

Follow-up observations are strongly encouraged.
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