TITLE: GCN CIRCULAR NUMBER: 17727 SUBJECT: Konus-Wind observation of GRB 150418A DATE: 15/04/22 13:12:44 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, and T. Cline on behalf of the Konus-Wind team, report: The long GRB 150418A localized by MAXI/GSC (Serino et al., GCN 17719) was detected by Konus-Wind in the waiting mode. The burst light curve shows a double-peaked structure started at ~T0(MAXI)-16 s with a total duration of ~29 s. As observed by Konus-Wind, the burst had a fluence of 2.94(-0.37,+0.47)x10^-6 erg/cm2 and a 2.944-s peak flux, measured from ~T0(MAXI)+5 s, of 2.71(-0.37,+0.49)x10^-7 erg/cm2/s (both in the 20 - 1200 keV energy range). Fitting the K-W 3-channel time-integrated spectrum (from ~T0(MAXI)-16 s to ~T0(MAXI)+14 s) by a simple power-law model yields a power law index of -2.24(-0.17,+0.17), chi2=0.04/1 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/GRB150418A/