TITLE: GCN CIRCULAR NUMBER: 44881 SUBJECT: Konus-Wind detection of GRB 260607B DATE: 26/06/09 11:26:57 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 260607B (Fermi-GBM detection: Fermi-GBM team, GCN 44859; Neights & Palafox, GCN 44861; Fermi-LAT detection: Holzmann Airasca et al., GCN 44860; AstroSat CZTI detection: Harsha et al., GCN 44871; GECAM-B detection: Wang et al., GCN 44880) triggered Konus-Wind at T0=47968.353 s UT (13:19:28.353). The burst light curve shows a bright multipeaked structure which starts at ~T0-6.8 s and ends at ~T0+50 s, which is followed by a weaker decaying emission with a 'bump' around ~T0+190 s. The total duration of the burst is ~209.8 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/GRB260607_T47968/ As observed by Konus-Wind, the burst had the total fluence of 4.55(-0.09,+0.09)x10^-4 erg/cm2, and the 64-ms peak flux, measured from T0+29.456 s, of 3.33(-0.27,+0.27)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+57.600 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 = -0.88(-0.02,+0.02), the high energy photon index beta = -2.87(-0.14,+0.11), the peak energy Ep = 622(-15,+16) keV (chi2 = 103/97 dof). The spectrum near the maximum count rate (measured from T0+29.184 to T0+30.720 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 = -0.74(-0.06,+0.06), the high energy photon index beta = -2.80(-0.37,+0.22), the peak energy Ep = 686(-51,+55) keV (chi2 = 48/62 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/44881. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...