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GCN Circular 22094

Subject
Konus-Wind observation of GRB 171102A
Date
2017-11-03T22:18:16Z (7 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, intense GRB 171102A
(Fermi-LAT detection: Yassine et al., GCN 22081;
Fermi GBM detection: Stanbro et al., GCN 22083;
IPN Triangulation: Kozlova et al., GCN 22091)
triggered Konus-Wind at T0=9247.579 s UT (02:34:07.579).

The burst light curve shows two emission episodes
with a total duration of ~28 s.
The emission is seen up to ~1 MeV.

As observed by Konus-Wind, the burst
had a fluence of 2.96(-0.32,+0.27)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+14.608 s,
of 5.87(-0.95,+0.96)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+21.760 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 = -0.76(-0.11,+0.11),
the high energy photon index beta = -2.98(-3.40,+0.31),
the peak energy Ep = 174(-12,+16) keV,
chi2 = 90/97 dof.

The spectrum near the peak count rate
(measured from T0+8.448 to T0+16.128 s)
is best fit in the 20 keV - 1.2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with�� alpha = -0.91(-0.12,+0.12),
and Ep = 203(-17,+21) keV (chi2 = 56/60 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.52 (chi2 = 56/59 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB171102_T09247/

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