TITLE: GCN CIRCULAR NUMBER: 15507 SUBJECT: Konus-Wind observation of GRB 131118A DATE: 13/11/21 08:06:58 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 131118A (Fermi GBM detection: Collazzi, GCN 15503; IPN triangulation: Hurley at al., GCN 15506) triggered Konus-Wind at T0=82738.919 s UT (22:58:58.919). The burst light curve shows multiple partly overlapped pulses from ~T0 to ~T0+140 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB131118_T82738/ Note: the waiting mode LCs are corrupted for almost whole duration of the burst. As observed by Konus-Wind, the burst had a fluence of (8.40 ± 0.06)x10-5 erg/cm2, and a 64-ms peak flux, measured from T0+63.296 s, of (5.1 ± 0.5)x10-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum (measured from T0 to T0+139.520 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.88 ± 0.05, the high energy photon index beta = -2.83 ± 0.25, the peak energy Ep = 230 ± 11 keV, chi2 = 97.4/96 dof. The spectrum near the maximum count rate (measured from T0+57.600 s to T0+65.792 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.80 ± 0.04, the high energy photon index beta = -2.56 ± 0.07, the peak energy Ep = 286 ± 8 keV, chi2 = 110/97 dof. All the quoted values are preliminary. [GCN OPS NOTE(21nov13) The GRB name was corrected to 131118A.]