TITLE: GCN CIRCULAR NUMBER: 44332 SUBJECT: Konus-Wind detection of GRB 260411B DATE: 26/04/17 17:11:27 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 260411B (Fermi-GBM detection: The Fermi GBM team, GCN 44262, Pathak & Sonawane, GCN 44266; BALROG localization: Preis & Greiner, GCN 44263; SVOM-GRM detection: Wang et al., GCN 44268; Fermi-LAT detection: Longo et al., GCN 44277; GECAM-B detection: Zao et al., GCN 44285; Glowbug detection: Woolf et al., GCN 44312; IPN triangulation: Kozyrev et al., GCN 44329) triggered Konus-Wind at T0=29079.388 s UT (08:04:39.388). The burst light curve shows a multipeaked structure which starts at ~T0-8.7 s and has a total duration of ~55.6 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260411_T29079/ As observed by Konus-Wind, the burst had a fluence of 4.50(-0.50,+0.50)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.440 s, of 1.15(-0.14,+0.14)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+49.408 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.62(-0.18,+0.19), the high energy photon index beta = -2.12(-0.19,+0.12), the peak energy Ep = 290(-38,+52) keV (chi2 = 82/98 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 the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.16(-0.15,+0.16), the high energy photon index beta = -2.19(-0.10,+0.08), the peak energy Ep = 248(-19,+23) keV (chi2 = 87/82 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/44332. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...