TITLE: GCN CIRCULAR NUMBER: 25660 SUBJECT: Konus-Wind observation of GRB 190829A DATE: 19/09/04 17:16:45 GMT FROM: Anastasia Tsvetkova at Ioffe Institute A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline on behalf of the Konus-Wind team, report: The long GRB 190829A which triggered Swift/BAT at T0=T0(BAT)=19:56:44.60 UT (Swift/BAT detection: Dichiara et al., GCN 25552; Lien et al., GCN 25579; Fermi GBM detection: Lesage et al., GCN 25575) was detected by Konus-Wind in the waiting mode. The burst light curve shows two emission episodes: the first pulse lasts from ~T0-51.6 s to ~T0-42.8 s, and the second pulse lasts from ~T0-4.5 s to ~T0+10.2 s. The total duration of the burst is ~61.8 s. As observed by Konus-Wind, the burst had a fluence of 1.29(-0.13,-0.15)x10^-5 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)-1.58 s, of 1.13(-0.11,+0.13)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Fitting the K-W 3-channel time-integrated spectrum (from ~T0(BAT)-51.628 s to ~T0(BAT)+10.196 s) in the 20 keV - 2 MeV range by a simple power law model yields the PL index = 2.30(-0.08,+0.09), chi2 = 0.61 / 1 dof. Modelling the K-W 3-channel spectrum of the initial pulse (from ~T0(BAT)-51.628 s to ~T0(BAT)-48.684 s) in the 20 keV - 2 MeV range by a power law with exponential cutoff model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.33(-0.23,+0.30), and Ep =579(-281,+2282) keV. Assuming the redshift z=0.0785 (ValeevĀ  et al., GCN 25565; De et al., GCN Circ. 25595) and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~2.0x10^50 erg, the peak luminosity L_iso is ~1.9x10^49 erg/s, and the rest-frame peak energy of the initial pulse spectrum, Ep,z, is ~624 keV. All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary. The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB190829A/