TITLE: GCN CIRCULAR NUMBER: 43590 SUBJECT: Konus-Wind detection of GRB 260131A/B DATE: 26/02/01 14:06:26 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru> 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 GRB 260131A/B (Fermi-GBM detection: The Fermi GBM team, GCN 43579, Roberts, GCN 43585; MAXI/GSC detection: Sugai et al., GCN 43580) triggered Konus-Wind (KW) at T0=23972.646 s UT (06:39:32.646). The burst consists of two separated emission pulses, peaked around ~T0 and to T0+215 s, respectively. The total duration of the burst is ~250 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260131_T23972/ As observed by Konus-Wind, the burst had a fluence of (4.14 ± 0.91)x10^-5 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 0.384 s, of (4.33 ± 0.52)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum (measured from T0 to T0+238 s) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.15 (-0.70,+1.61), the high energy photon index beta = -1.97 (-0.20,+0.14), the peak energy Ep = 124 (-40,+56) keV, chi2 = 83/97 dof. The spectrum near the peak count rate (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.17 (-0.15,+0.17), the high energy photon index beta = -1.98 (-0.18,+0.10), the peak energy Ep = 300 (-68,+131) keV, chi2 = 74/79 dof. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/43590. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...