TITLE: GCN CIRCULAR NUMBER: 44167 SUBJECT: Konus-Wind detection of GRB 260320A DATE: 26/03/31 13:34:05 GMT FROM: Valentina Panteleeva at Ioffe Institute <panteleevav228@gmail.com> V. Panteleeva, D. Frederiks, A. Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 260320A (NuSTAR detection: Waratkar et al., GCN 44064, Insight-HXMT/HE detection: Luo et al., GCN 44077, Glowbug gamma-ray detection: Cheung et al., GCN 44093, GRID detection: Li et al., GCN 44109, IPN triangulation: Kozyrev et al., GCN 44121) triggered Konus-Wind at T0=70801.257 s UT (19:40:01.257). The burst light curve shows a single pulse which starts at ~T0-0.4 s and has a total duration of ~13.1 s. The emission is seen up to ~1 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260320_T70801/ As observed by Konus-Wind, the burst had the total fluence of 1.88(-0.20,+0.19)x10^-5 erg/cm2, and the 64-ms peak flux, measured from T0+0.896 s, of 6.92(-0.78,+0.80)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 the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.18(-0.10,+0.10), the high energy photon index beta = -2.44(-0.43,+0.18), the peak energy Ep = 267(-32,+45) keV (chi2 = 86/91 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: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.33(-0.06,+0.06) and Ep = 359(-36,+44) keV (chi2 = 82/77 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.29 (chi2 = 82/76 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/44167. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...