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GCN Circular 18723

Subject
Konus-Wind observation of GRB 151222A
Date
2015-12-25T12:52:22Z (8 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration, hard-spectrum GRB 151222A
(Fermi GBM detection: Hoi-Fung Yu, GCN Circ. 18715;
IPN triangulation: Hurley, et al., GCN Circ. 18720)
triggered Konus-Wind at T0=29415.138  s UT (08:10:15.138).

The burst light curve shows a double-peaked structure
with a total duration of ~0.5 s.

As observed by Konus-Wind, the burst
had a fluence of 2.20(-0.23,+0.28)x10^-6 erg/cm2
and a 16-ms peak flux, measured from T0+0.048 s,
of 1.03(-0.11,+0.13)x10^-5 erg/cm2/s
(both in the 20 - 1500 keV energy range).

Since a major fraction of the burst counts was accumulated
before the trigger, the spectral analysis was performed using
the KW 3-channel light curve data.
Modeling the 3-channel time-integrated spectrum
(measured from T0-0.434 s to T0+0.094 s)
by the cutoff power law yields the following model parameters:
the photon index alpha=0.13(-0.44,+0.64),
and the peak energy Ep=625(-118,+220) keV.

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.

The K-W light curve of this burst is available at
http://www.ioffe.ru/LEA/GRBs/GRB151222_T29415/
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