TITLE: GCN CIRCULAR NUMBER: 23456 SUBJECT: Konus-Wind observation of GRB 181121A DATE: 18/11/26 14:55:41 GMT FROM: Anna Kozlova at Ioffe Institute A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 181121A (AGILE/MCAL detection: Ursi et al., GCN 23429; AstroSat CZTI detection: Sharma et al., GCN 23447; IPN Triangulation: Kozlova et al., GCN 23449) triggered Konus-Wind at T0=74619.153 s UT (20:43:39.153). The burst light curve shows a multipeaked structure which starts at ~T0 s and has a total duration of ~1.4 s. The emission is seen up to ~2 MeV. As observed by Konus-Wind, the burst had a fluence of 1.46(-0.26,+0.44)x10^-5 erg/cm2, and a 16-ms peak flux, measured from T0+0.118 s, of 9.44(-1.53,+1.77)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.83(-0.20,+0.46), the high energy photon index beta = -2.58(-1.04,+0.46), the peak energy Ep = 226(-65,+45) keV (chi2 = 72/56 dof). The spectrum near the maximum count rate (measured from T0+0.064 to T0+0.192 s) is best fit in the 20 keV - 2 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.27(-0.24,+0.32), the high energy photon index beta = -2.54(-0.47,+0.28), the peak energy Ep = 271(-47,+50) keV (chi2 = 57/42 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB181121_T74619/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.