TITLE: GCN CIRCULAR NUMBER: 27631 SUBJECT: Konus-Wind observation of a bright burst from SGR 1935+2154 DATE: 20/04/23 13:21:05 GMT FROM: Anna Ridnaia at Ioffe Institute A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The bright burst from SGR 1935+2154 (CALET-GRBM detection: Cherry et al., GCN Circ. 27623; IPN triangulation: Hurley et al., GCN Circ. 27625) triggered Konus-Wind at T0=31996.933 s UT (08:53:16.933) on 2020 April 22. The light curve shows a single pulse with a sharp rise and a total duration of ~0.6 s. The emission is seen up to ~250 keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/SGRs/200422_T31996/ As observed by Konus-Wind, the burst had a fluence of 1.15(-0.03,+0.03)x10^-5 erg/cm2, and a 16-ms peak flux, measured from T0+0.072 s, of 2.75(-0.23,+0.23)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 = -0.06(-0.24,+0.25) and Ep = 52(-2,+2) keV (chi2 = 30/25 dof). A double blackbody function fits this spectrum less well (chi2 = 40/24 dof), with the cold BB temperature of 9.4 (-4.5,+1.9) keV and the hot BB temperature of 18.9 (-3.7,+5.3) keV. Among 17 bright bursts from SGR 1935+2154 detected by KW so far this event is the second most fluent (after the April 12, 2015 Intermediate Flare; Kozlova et al. 2016, MNRAS 460, 2008) and the second most luminous (after the November 5, 2019 burst; Ridnaia et al., GCN 26242). Also, the spectrum of the burst is characterized by the hardest peak energy so far; a typical Ep(CPL) for the KW sample is in the 30-40 keV range. All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.