TITLE: GCN CIRCULAR NUMBER: 18259 SUBJECT: Konus-Wind observation of GRB 150906B DATE: 15/09/08 18:12:45 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A.Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The short-duration, hard-spectrum GRB 150906B (IPN triangulation: Hurley, et al., GCN 18258) triggered Konus-Wind at 31340.560 s UT (08:42:20.560). The KW light curve shows a single, multi-peaked pulse with a duration of ~2 s. The emission is visible up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB150906_T31340/ As observed by Konus-Wind, the burst had a fluence of 2.8(-0.2,+0.2)x10^-5 erg/cm2, and a 16-ms peak flux, measured from T0+1.488 s, of 2.9(-0.3,+0.3)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 15 MeV range by the cutoff power law with the following model parameters: the photon index alpha = -0.43(-0.11,+0.12), and the peak energy Ep = 928(-95,+111) keV, chi2 = 93/94 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep with an upper limit on beta of -2.8 All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.