TITLE: GCN CIRCULAR NUMBER: 44887 SUBJECT: Konus-Wind detection of GRB 260604C DATE: 26/06/09 16:52:29 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 260604C (Fermi-GBM detection: Fermi GBM team, GCN 44822, Neights et al., GCN 44831; SVOM-ECLAIRs detection: Gotz et al., GCN 44823, Brunet et al., GCN 44883; GECAM-B detection: Luo et al., GCN 44854; AstroSat-CZTI detection: Arya et al., GCN 44885) triggered Konus-Wind at T0=73128.568 s UT (20:18:48.568). The burst light curve shows a single pulse which starts at ~T0-3.2 s and has a duration of ~8.5 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/GRB260604_T73128/ As observed by Konus-Wind, the burst had the total fluence of 3.60(-0.26,+0.26)x10^-5 erg/cm2, and the 64-ms peak flux, measured from T0+3.056 s, of 2.25(-0.18,+0.18)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+12.032 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 = -0.92(-0.05,+0.06), the high energy photon index beta = -2.33(-0.19,+0.13), the peak energy Ep = 421(-37,+40) keV (chi2 = 82/89 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+3.840 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 = -0.73(-0.06,+0.06), the high energy photon index beta = -2.07(-0.07,+0.06), the peak energy Ep = 374(-32,+35) keV (chi2 = 60/71 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/44887. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...