TITLE: GCN CIRCULAR NUMBER: 20643 SUBJECT: Konus-Wind observation of GRB 170208B DATE: 17/02/09 14:39:18 GMT FROM: Dmitry Svinkin at Ioffe Institute 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 170208B (Swift-BAT detection: Siegel et al., GCN Circ. 20632) triggered Konus-Wind at T0=81222.750 s UT (22:33:42.750). The burst light curve shows a single emission episode started at ~T0-5 s with a total duration of ~11 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_T81222/ As observed by Konus-Wind, the burst had a fluence of 8.17(-0.44,+0.46)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+1.072 s, of 2.55(-0.82,+0.82)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 - 1 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.78(-0.23,+0.25) and Ep = 105(-7,+8) keV (chi2 = 40/51 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.0 (chi2 = 39/50 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.