TITLE: GCN CIRCULAR NUMBER: 18326 SUBJECT: Konus-Wind observation of GRB 150911A DATE: 15/09/17 04:21:46 GMT FROM: Anastasia Tsvetkova 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 long-duration GRB 150911A (Swift-BAT trigger #655262: Starling, et al., GCN Circ. 18280; Markwardt , et al., GCN Circ. 18292) was detected by Konus-Wind in the waiting mode. The burst light curve shows a single pulse with a total duration of ~9 s. As observed by Konus-Wind, the burst had a fluence of 3.13(-0.20,+0.26)x10^-6 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)+2.5 s, of 4.01(-0.32,+0.59)x10^-7 erg/cm2/s (both in the 20 - 1000 keV energy range). Fitting the K-W 3-channel time-integrated spectrum (measured from ~T0(BAT)-0.5 s to ~T0(BAT)+8.5 s) by a simple power-law model yields the photon index -2.32(-0.09,+0.09), chi2=0.6/1 dof. All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary. The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB150911A/ [GCN OPS NOTE(16sep15): This circular was delayed ~12 hours in distribution because of an operation mistake at GCN.]