[vsnet-grb-info 19096] Konus-Wind observation of GRB 170208A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20641
SUBJECT: Konus-Wind observation of GRB 170208A
DATE:    17/02/09 14:34:23 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin at mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170208A
(Swift-BAT detection: Cholden-Brown et al., GCN Circ. 20631;
Fermi-GBM detection: Roberts and Meegan, GCN Circ. 20633)
triggered Konus-Wind at T0=65479.756 s UT (18:11:19.756).

The burst light curve shows a multipeaked structure
started at ~T0-0.4 s with a total duration of ~8 s.
The emission is seen up to ~1 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170208_T65479/

As observed by Konus-Wind, the burst
had a fluence of 2.62(-0.31,+0.37)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0-0.012 s,
of 1.94(-0.65,+0.67)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.52(-0.46,+0.56)
and Ep = 153(-24,+36) keV (chi2 = 67/60 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 67/59 dof)

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