TITLE: GCN CIRCULAR NUMBER: 30804 SUBJECT: Konus-Wind detection of the second intermediate flare from SGR 1935+2154 DATE: 21/09/10 21:03:57 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru> A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The very bright burst from SGR 1935+2154 (IPN triangulation: Ridnaia et al., GCN Circ. 30803) triggered Konus-Wind at T0=2750.499 s UT (00:45:50.499) on 2021 September 10. The light curve shows a single pulse with a sharp(<10 ms) rise and a total duration of ~1.4 s. The emission is seen up to ~200 keV. The Konus-Wind light curve of this burst is available at http://www.ioffe.ru/LEA/SGRs/210910_T02750/ As observed by Konus-Wind, the burst had a fluence of 2.51(-0.04,+0.04)x10^-5 erg/cm2, and a 16-ms peak flux, measured from T0+0.322 s, of 3.09(-0.18,+0.18)x10^-5 erg/cm2/s (both in the 20 - 500 keV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.512 s) is best fit in the 20 - 200 keV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = 0.21(-0.18,+0.19) and Ep = 52(-1,+1) keV (chi2 = 37/22 dof). The rather long duration of the burst along with the large measured energy fluence put the burst in the class of "intermediate" SGR bursts. The event is as fluent as the April 12, 2015 Intermediate Flare (Kozlova et al. 2016, MNRAS 460, 2008); the spectrum of the burst is characterized by the higher peak energy than of the April 12, 2015 IF (Ep~35 keV). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.