TITLE: GCN CIRCULAR NUMBER: 18401 SUBJECT: Konus-Wind observation of GRB 151001B DATE: 15/10/06 11:18:10 GMT FROM: Anna Kozlova 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: At ~16 minutes before the Swift-BAT trigger on GRB 151001B (Krimm, et al., GCN Circ. 18374; T0(BAT)=18:29:36 UT) Konus-Wind detected, in the waiting mode, a burst of high X-ray/soft gamma-ray emission which had a duration of ~191 s. Taking into account the proximity of this burst to the Swift-BAT trigger and consistency of the KW ecliptic latitude response with the position of GRB 151001B we suggest this burst is the main part of GRB 151001B. The K-W light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB151001B/ The count rate increase in the soft KW energy band, which follows the burst from T0(BAT)-838 s to T0(BAT)+2488 s, can not be unambiguously attributed to GRB 151001B. As observed by Konus-Wind, the burst had a fluence of 8.5(-2.3,+0.6)x10^-6 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)-1007.1 s, of 1.8(-0.6,+0.4)x10^-7 erg/cm2/s (both in the 20 - 1000 keV energy range). Modeling the K-W 3-channel time-integrated spectrum (from T0(BAT)-1018.9 s to T0(BAT)-827.5 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -0.9(-0.3,+0.5) and Ep = 179 (-52,+75) keV. All the quoted errors are at 1 sigma confidence level. All the quoted values are preliminary.