TITLE: GCN CIRCULAR NUMBER: 13870 SUBJECT: Konus-Wind observation of GRB 121011B DATE: 12/10/15 11:10:07 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 short-duration hard-spectrum GRB 121011B (IPN localization: Golenetskii at al., GCN 13863) triggered Konus-Wind at T0=81140.083s UT (22:32:20.083) The light curve shows a single pulse with a duration of ~0.35 s. The emission is seen up to ~7 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB121011_T81140/ As observed by Konus-Wind the burst had a fluence of (2.8 ± 0.3)x10-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.112 s, of (2.3 ± 0.4)x10-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The spectrum of the burst (measured T0 to T0+0.192 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.45 ± 0.37, the high energy photon index beta = -1.9 ± 0.4, the peak energy Ep = 670 ± 340 keV, chi2 = 16.3/17 dof. All the quoted results are preliminary.