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GCN Circular 17982

Subject
Konus-Wind observation of GRB 150627A
Date
2015-06-29T14:29:44Z (9 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
S. Golenetskii, R. Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, bright GRB 150627A
(Fermi-LAT detection: Arimoto, et al., GCN Circ. 17971;
Fermi-GBM detection: Yu, GCN Circ. 17975)
triggered Konus-Wind at T0=15806.292 s UT (04:23:26.292).

The burst light curve shows a bright multi-peaked structure
from ~T0-6 s to ~T0+80 s followed by a weak tail,
which is traceable out to ~T0 + 150 s.
The emission is seen up to ~15 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150627_T15806/

As observed by Konus-Wind, the burst
had a fluence of 2.34(-0.11,+0.12)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+12.240 s,
of 2.02(-0.27,+0.27)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+81.408 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.98(-0.04,+0.05),
the high energy photon index beta = -2.25(-0.08,+0.07),
the peak energy 217(-13,+14) keV
(chi2 = 125/96 dof)

The spectrum near the maximum count rate
(measured from T0+9.728 to T0+12.800 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.55(-0.07,+0.08),
the high energy photon index beta = -2.52(-0.29,+0.18),
the peak energy 412(-38,+40) keV
(chi2 = 114/94 dof)

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