TITLE: GCN CIRCULAR NUMBER: 20082 SUBJECT: Konus-Wind observation of GRB 161017A DATE: 16/10/19 17:42:56 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 161017A (Swift-BAT trigger #718023: Troja et al., GCN 20064, T0(BAT)=17:51:51 UT; Fermi-GBM observation: Hui & Meegan, GCN 20068; Lomonosov observation: Sadovnichy et al., GCN 20075) was detected by Konus-Wind in the waiting mode. The light curve shows an emission pulse which starts ~10 s before the BAT trigger, peaks at ~T0(BAT)+7 s, and lasts till ~T0(BAT)+28 s. The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB161017_T64311/ As observed by Konus-Wind, the burst had a fluence of (8.5 ± 1.1)x10^-6 erg/cm2 and a 2.944-s peak energy flux, measured from ~T0(BAT)+7 s, of (8.7 ± 0.2)x10^-7 erg/cm2 (both in the 20 - 10000 keV energy range). Modeling the KW 3-channel time-integrated spectrum (from T0(BAT)-10 s to T0(BAT)+28 s) by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.25 ± 0.16, and Ep = 289 ± 73 keV. Modeling the KW 3-channel spectrum near the peak count rate with the CPL model yields alpha = -1.17 ± 0.20, and Ep = 404 ± 136 keV. Assuming the redshift z=2.013 (de Ugarte Postigo et al., GCN 20069) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7, we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~8.3x10^52 erg, the peak luminosity L_iso is ~2.5x10^52 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is ~870 keV. All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary.