TITLE: GCN CIRCULAR NUMBER: 19977 SUBJECT: Konus-Wind observation of GRB 161001A (short/hard ?) DATE: 16/10/02 11:46:33 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report: GRB 161001A (Swift/BAT detection: Page et al., GCN 19967; Fermi GBM observation: Veres et al., GCN 19973) triggered Konus-Wind at T0=3919.479 s UT (01:05:19.479). The light curve shows a short pulse with a total duration of ~0.5 s. The emission is seen up to ~5 MeV. As observed by Konus-Wind, the burst had a fluence of (1.8 ± 0.5)x10^-6 erg/cm2 and a 16-ms peak energy flux, measured from T0-0.016, of (8.0 ± 3.5)x10^-6 erg/cm2 (both in the 20 keV - 10 MeV energy range). The spectrum of the burst (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by a cutoff power-law (CPL) function with the following model parameters: the photon index alpha = -0.46(-0.36,+0.48), and the peak energy Ep = 437(-117,+190) keV, chi2 = 30.0/36 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep with only an upper limit on beta of -2.1, chi2 = 30.0/35 dof. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB161001_T03919/ All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.