TITLE: GCN CIRCULAR NUMBER: 45242 SUBJECT: Konus-Wind detection of GRB 260727A DATE: 26/07/28 12:56:48 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, V. Panteleeva, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 260727A (SVOM-ECLAIRs detection: Li et al., GCN 45220; AstroSat-CZTI detection: Harsha et al., GCN 45225; Glowbug detection: Cheung et al., GCN 45233) triggered Konus-Wind at T0=1327.631 s UT (00:22:07.631). The burst light curve shows a multi-peaked structure which starts at ~T0-11 s and has a total duration of ~30 s (75-1200 keV). The emission is seen up to ~300 keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260727_T01327/ As observed by Konus-Wind, the burst had the total fluence of 1.15(-0.03,+0.03)x10^-5 erg/cm2, and the 64-ms peak flux, measured from T0+1.072 s, of 1.61(-0.30,+0.30)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 = -0.20(-0.11,+0.11) and Ep = 85(-2,+2) keV (chi2 = 107/98 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -4.2 (chi2 = 107/97 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: with alpha = 0.02(-0.14,+0.14) and Ep = 93(-3,+3) keV (chi2 = 80/82 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.8 (chi2 = 80/81 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/45242. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...