TITLE: GCN CIRCULAR NUMBER: 13676 SUBJECT: Konus-Wind observation of GRB 120816B DATE: 12/08/18 14:52:56 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 exceptionally intense GRB 120816B (IPN localization: Golenetskii at al., GCN 13675) triggered Konus-Wind at T0=86298.852s UT (23:58:18.852) The light curve shows a single multi-peaked pulse. A total duration of the burst in is ~0.8 s (80-350 keV range) with a hint of a soft extended tail lasting till ~T0+50 s. The emission in the main phase of the burst is seen up to ~9 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB120816_T86298/ As observed by Konus-Wind the burst had a fluence of 9.7(-0.5,+0.5)x10-5 erg/cm2, and a 16-ms peak flux, measured from T0, of 2.3(-0.2,+0.2)x10-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+0.768 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model, for which alpha = -0.61 (-0.04, +0.04), and Ep = 2320(-130, +140) keV, chi2 = 100/89 dof. All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.