TITLE: GCN CIRCULAR NUMBER: 21299 SUBJECT: Konus-Wind observation of GRB 170705A DATE: 17/07/06 11:16:24 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 170705A (Swift-BAT observation: Starling et al., GCN Circ. 21289; Fermi-GBM observation: Bissaldi and Meegan, GCN Circ. 21297) triggered Konus-Wind at T0=9956.188 s UT (02:45:56.188). The burst light curve shows a bright, multipeaked pulse, which starts at ~T0-6 s and has a total duration of ~25 s, followed by a weaker emission seen up to ~T0+300 s. The emission in the main episode is seen up to ~1 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170705_T09956/ As observed by Konus-Wind, the burst had a fluence of 1.76(-0.19,+0.20)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+2.384 s, of 4.21(-0.94,+0.96)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the main episode (measured from T0 to T0+24.832 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 = -1.31(-0.17,+0.20) and Ep = 155(-22,+31) keV (chi2 = 53/62 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 = 59/61 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model: with alpha = -1.16(-0.15,+0.16) and Ep = 166(-18,+23) keV (chi2 = 69/61 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 (chi2 = 69/60 dof). Assuming the redshift z=2.010 (de Ugarte Postigo et al., GCN Circ. 21298) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~1.8x10^53 erg, the peak luminosity L_iso is ~1.3x10^53 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is ~466 keV. All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.