TITLE: GCN CIRCULAR NUMBER: 12701 SUBJECT: Konus-Wind observation of GRB 111215B DATE: 11/12/17 12:20:31 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long intense GRB 111215B (localized by IPN: Hurley et al., GCN 12698) triggered Konus-Wind at T0=72682.720s UT (20:28:02.720) The light curve shows multiple partly overlapping pulses with the brightest peak at ~T0+12s. A total duration of the burst is ~75 s. The emission is seen up to ~8 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB111215_T73682/ As observed by Konus-Wind the burst had a fluence of 5.3(-1.1,+1.1)x10-5 erg/cm2, and a 256-ms peak flux, measured from T0+11.776 s, of 6.1(-0.6,+0.6)x10-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+72.192 s) is best fitted in the 20 keV - 10 MeV range with the GRB (Band) model, for which: the low-energy photon index alpha = -1.18 (-0.12, +0.18), the high energy photon index beta = -2.3 (-0.6, +0.2), the peak energy Ep = 250(-60, +65) keV, chi2 = 88.2/88 dof. The spectrum at the maximum count rate (measured from T0+7.680 to T0+14.848 s) is best fitted in the 20 keV - 10 MeV range by a power law with exponential cutoff model, for which alpha = -1.03 (-0.10, +0.11), and Ep = 413(-57, +75) keV, chi2 = 101.9/89 dof. Fitting this spectrum by the GRB (Band) function yields the same alpha and Ep with a high energy photon index beta < -2.6 (chi2 = 101.9/88 dof). All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.