TITLE: GCN CIRCULAR NUMBER: 19613 SUBJECT: Konus-Wind observation of a bright burst from SGR 1935+2154 DATE: 16/06/28 14:29:17 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 bright burst from SGR 1935+2154 (Swift detection: Barthelmy et al., GCN 19590; Cummings et al., GCN 19596; Fermi/GBM detection: Younes et al., GCN 19598) triggered Konus-Wind at T0=50073.909 s UT (13:54:33.909) on 2016 June 26. The light curve shows a single pulse with a sharp rise and a total duration of ~0.8 s. The emission is seen up to ~200 keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/SGRs/160626_T50073/ As observed by Konus-Wind, the burst had a fluence of 1.28(-0.02,+0.02)x10^-5 erg/cm2, and a 16-ms peak flux, measured from T0, of 2.1(-0.1,+0.1)x10^-5 erg/cm2/s (both in the 20 - 200 keV energy range). The burst spectrum (measured from T0 to T0+0.256 s) is well fit by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.17(-0.16,+0.16), and Ep = 37.5(-1.1,+1.0) keV (c-stat = 16.1/25 dof). A double blackbody function fits this spectrum equally well (c-stat = 17.3/26 dof), with the cold BB temperature of 6.6 (-0.6,+0.6) keV and the hot BB temperature of 13.9 (-0.6,+0.8) keV. This event continues a series of about a dozen bright bursts from SGR 1935+2154 detected by Konus-Wind in May-June, 2016. Varying in their durations and energy fluences, these bursts demonstrate spectral properties and peak luminosities similar to those of the 1.7s-long "intermediate" flare (IF) from this source (Kozlova et al. 2016, MNRAS 460, 2008). All the quoted errors are at the 1 sigma confidence level. All the quoted values are preliminary.