TITLE: GCN CIRCULAR NUMBER: 12585 SUBJECT: Konus-Wind observation of GRB 111121A DATE: 11/11/23 12:26:06 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 hard intense GRB 111121A (Swift-BAT trigger #508161: D'Elia et al., GCN 12578; Cummings et al., GCN 12581) triggered Konus-Wind at T0=59182.640s UT (16:26:22.640) The light curve shows of a hard bright pulse with a total duration of ~600 ms followed by a tail of a weak soft extended emission for at 20 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/GRB111121_T59182/ As observed by Konus-Wind the burst had a fluence of (2.3 ± 0.3)x10-5 erg/cm2, and a 16-ms peak flux, measured from T0+0.160 s, of (8.4 ± 1.5)x10-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The spectrum of the burst (measured from T0 to T0+0.256 s) is best fitted in the 20 keV - 10 MeV range with the GRB (Band) model, for which: the low-energy photon index alpha = -0.44 (-0.07, +0.07), the high energy photon index beta = -3.0 (<-2.4), the peak energy Ep = 1780(-290, +310) keV, chi2 = 59.7/51 dof. All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.