TITLE: GCN CIRCULAR NUMBER: 23495 SUBJECT: Konus-Wind observation of GRB 181201A DATE: 18/12/03 16:42:48 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 181201A (INTEGRAL-IBIS/ISGRI detection: Mereghetti et al., GCN Circ. 23469; Insight-HXMT/HE detection: Cai et al., GCN Circ. 23491) triggered Konus-Wind at T0=9592.355 s UT (02:39:52.355). The burst light curve consists of two well-separated pulses with the first pulse staring at ~T0-115 s, and a total burst duration of ~172 s. The emission is seen up to ~15 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB181201_T09592/ As observed by Konus-Wind, the burst had a fluence of 1.99(-0.06,+0.06)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+4.848 s, of 2.88(-0.33,+0.34)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+34.816 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.25(-0.05,+0.05), the high energy photon index beta = -2.73(-0.12,+0.11), the peak energy Ep = 152(-6,+6) keV (chi2 = 114/97 dof). The spectrum near the maximum count rate (measured from T0+4.352 to T0+4.864 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.75(-0.16,+0.19), the high energy photon index beta = -2.76(-0.38,+0.21), the peak energy Ep = 207(-24,+26) keV (chi2 = 51/49 dof). Assuming the redshift z=0.450 (Izzo et al., GCN Circ. 23488) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~1.0x10^53 erg, the peak luminosity L_iso is ~2.2x10^52 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is ~220 keV. All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.