TITLE: GCN CIRCULAR NUMBER: 20935 SUBJECT: Konus-Wind observation of GRB 170320A DATE: 17/03/23 11:06:28 GMT FROM: Anastasia Tsvetkova at Ioffe Institute 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, intense GRB 170320A (IPN Triangulation: Hurley et al., GCN 20927; POLAR Observation: Zhao et al., GCN 20934) triggered Konus-Wind at T0=13359.957 s UT (03:42:39.957). The burst light curve shows a multipeaked structure with a total duration of ~30 s. The emission is seen up to ~5 MeV. As observed by Konus-Wind, the burst had a fluence of 1.87(-0.30,+0.34)x10^-5 erg/cm2, and a 64-ms peak energy flux, measured from T0+0.592 s, of 1.01(-0.19,+0.20)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+35.072 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.35(-0.15,+0.21), the high energy photon index beta = -2.41(-0.46,+0.22), the peak energy Ep = 111(-22,+23) keV, chi2 = 99/97 dof. The spectrum near the peak count rate (measured from T0 to T0+2.304 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.52(-0.17,+0.20), the high energy photon index beta = -2.21(-0.18,+0.13), the peak energy Ep = 178(-24,+29) keV, chi2 = 79/69 dof. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170320_T13359/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.