TITLE: GCN CIRCULAR NUMBER: 44967 SUBJECT: Konus-Wind detection of GRB 260616A DATE: 26/06/17 15:37:03 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 260616A (Fermi-GBM detection: Fermi GBM team, GCN 44948; BALROG localization: Preis & Greiner, GCN 44949; Fermi-LAT detection: Lopez et al., GCN 44960; GECAM-B detection: Guo et al., GCN 44964) triggered Konus-Wind at T0=12085.625 s UT (03:21:25.625). The burst light curve shows a bright, multipeaked pulse, which starts at ~T0-63 s and has a total duration of ~292 s. A weaker possible precursor is clearly visible in the KW waiting mode data around ~T0-422 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/GRB260616_T12085/ As observed by Konus-Wind, the burst had the total fluence of 2.77(-0.09,+0.09)x10^-4 erg/cm2, and the 64-ms peak flux, measured from T0+82.880 s, of 7.35(-1.24,+1.23)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+105.984 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 = -0.76(-0.03,+0.04), the high energy photon index beta = -2.28(-0.06,+0.05), the peak energy Ep = 295(-10,+11) keV (chi2 = 118/97 dof). The spectrum near the maximum count rate (measured from T0+81.408 to T0+89.600 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 = -0.97(-0.08,+0.09), the high energy photon index beta = -2.23(-0.25,+0.15), the peak energy Ep = 379(-49,+57) keV (chi2 = 87/87 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/44967. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...