GCN Circular 19244
Subject
Konus-Wind observation of GRB 160325A
Date
2016-03-29T13:44:26Z (8 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 GRB 160325A
(Swift-BAT trigger #680436: Sonbas, Lien & Page, GCN 19222;
Fermi GBM detection: Roberts, GCN 19224;
Fermi-LAT detection: Axelsson et al., GCN 19227)
triggered Konus-Wind at T0=25162.835 s UT (06:59:22.835).
The burst light curve shows two emission episodes,
a total duration of the burst (80-360 keV) is ~45 s.
The emission is seen up to ~1.5 MeV.
As observed by Konus-Wind, the burst
had a fluence of 1.73(-0.12,+0.14)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+10.304 s,
of 3.04(-1.04,+1.08)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+49.408 s)
is best fit in the 20 keV - 1.5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.93(-0.14,+0.15),
and Ep = 214(-23,+31) keV (chi2 = 69/60 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.45 (chi2 = 69/59 dof).
The spectrum near the peak count rate
(measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.76(-0.15,+0.18),
the high energy photon index beta = -2.47(-0.59,+0.26),
the peak energy Ep = 207(-26,+32) keV,
chi2 = 70/57 dof.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160325_T25162/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.