TITLE: GCN CIRCULAR NUMBER: 45496 SUBJECT: Konus-Wind detection of GRB 260829A DATE: 26/09/02 11:12:15 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, V. Panteleeva, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 260829A (Fermi-GBM detection: Fermi GBM team, GCN 45464; Malacaria et al., GCN 45467; BALROG localization: Preis & Greiner, GCN 45465; GECAM-B detection: Zao et al., GCN 45470; IPN triangulation: Kozyrev et al., GCN 45476; AstroSat CZTI detection: Goyal et al., GCN 45485; SVOM-GRM detection: Luo et al., GCN 45495) triggered Konus-Wind at T0=22110.076 s UT (06:08:30.076). The burst light curve shows an initial weak emission episode starting at ~T0-21.3 s, followed by a brighter multi-peaked structure. The total burst duration is ~34.8 s. The emission is seen up to ~4 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260829_T22110/ As observed by Konus-Wind, the burst had the total fluence of 2.05(-0.09,+0.10)x10^-5 erg/cm2, and the 64-ms peak flux, measured from T0+2.208 s, of 8.44(-0.91,+0.92)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+16.640 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.94(-0.09,+0.09) and Ep = 330(-24,+28) keV (chi2 = 114/98 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.8 (chi2 = 114/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+8.448 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.75(-0.08,+0.08) and Ep = 314(-17,+19) keV (chi2 = 122/88 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.0 (chi2 = 122/87 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/45496. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...