TITLE: GCN CIRCULAR NUMBER: 22005 SUBJECT: Konus-Wind observation of GRB 171011B DATE: 17/10/12 13:27:38 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration, very intense GRB 171011B (IPN triangulation: Hurley et al., GCN Circ. 21998) triggered Konus-Wind at T0=3931.430 s UT (01:05:31.430). The burst light curve shows a multipeaked structure which starts at ~T0-7.3 s and has a total duration of ~18.2 s. The emission is seen up to ~20 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB171011_T03931/ As observed by Konus-Wind, the burst had a fluence of 7.02(-0.56,+0.57)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.456 s, of 5.55(-0.61,+0.62)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+10.496 s) is best fit in the 20 keV - 20 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.54(-0.12,+0.14), the high energy photon index beta = -2.28(-0.16,+0.12), the peak energy Ep = 315(-33,+37) keV (chi2 = 98/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+1.792 s) is best fit in the 20 keV - 20 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.51(-0.11,+0.14), the high energy photon index beta = -2.59(-0.34,+0.21), the peak energy Ep = 416(-48,+50) keV (chi2 = 78/65 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.