TITLE: GCN CIRCULAR NUMBER: 44585 SUBJECT: Konus-Wind detection of GRB 260511A DATE: 26/05/12 16:55:02 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 260511A (Fermi-GBM detection: Fermi GBM team, GCN 44529; Roberts et al., GCN 44548; BALROG localization: Preis & Greiner, GCN 44531; SVOM detection: Godet et al., GCN 44532; NuSTAR detection: Waratkar et al., GCN 44555) triggered Konus-Wind at T0=22416.401 s UT (06:13:36.401). The burst light curve shows a multipeaked structure which starts at ~T0-4.6 s and has a total duration of ~20.5 s. The emission is seen up to ~6 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260511_T22416/ As observed by Konus-Wind, the burst had a fluence of 1.72(-0.05,+0.05)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+0.482 s, of 6.96(-0.71,+0.71)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 = -0.79(-0.08,+0.09) and Ep = 187(-8,+8) keV (chi2 = 107/99 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.1 (chi2 = 107/98 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 = -0.66(-0.08,+0.08) and Ep = 187(-6,+7) keV (chi2 = 88/86 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.9 (chi2 = 87/85 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/44585. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...