{
  "circularId": 43864,
  "eventId": "GRB 260226A",
  "submitter": "Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>",
  "bibcode": "2026GCN.43864....1S",
  "createdOn": 1772200376756,
  "submittedHow": "web",
  "subject": "Konus-Wind detection of GRB 260226A",
  "body": "D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,\nA. Tsvetkova, M. Ulanov, and T. Cline\non behalf of the Konus-Wind team, report:\n\nThe bright, long-duration GRB 260226A\n(Fermi-GBM detection: The Fermi GBM team, GCN 43840;\nBissaldi eat al., GCN 43851;\nBALROG localization: Preis and Greiner, GCN 43843;\nFermi-LAT detection: Depalo et al., GCN 43844, 43850;\nAstroSat-CZTI detection: Harsha et al., GCN 43846;\nNuSTAR-ACS detection: Waratkar et al., GCN 43854;\nGlowbug detection: Woolf et al., GCN 43855;\nCALET-GBM detection: Kobayashi et al., GCN 43860)\ntriggered Konus-Wind at T0=38287.440 s UT (10:38:07.440).\n\nThe burst light curve shows a very bright, multi-peaked\nemission pulse which starts at ~T0-9 s and has a duration of ~30 s.\nThis pulse is followed by a weaker, smoothly decaying emission tail,\nvisible up to the end of the KW triggered data record (~T0+250 s).\nThe emission is seen up to ~20 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB260226_T38287/\n\nAs observed by Konus-Wind, the burst\nhad the total fluence of 7.27(-0.17,+0.17)x10^-4 erg/cm2,\nand the 64-ms peak flux, measured from T0+10.688 s,\nof 1.33(-0.06,+0.06)x10^-4 erg/cm2/s\n(both in the 20 keV - 10 MeV energy range).\n\nThe time-averaged spectrum of the burst\n(measured from T0 to T0+142.080 s)\nis best fit in the 20 keV - 10 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.93(-0.02,+0.03),\nthe high energy photon index beta = -2.33(-0.07,+0.06),\nthe peak energy Ep = 613(-25,+26) keV\n(chi2 = 118/97 dof).\n\nThe spectrum near the maximum count rate\n(measured from T0+10.240 to T0+10.752 s)\nis best fit in the 20 keV - 10 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.64(-0.06,+0.07),\nthe high energy photon index beta = -2.11(-0.08,+0.07),\nthe peak energy Ep = 772(-77,+80) keV\n(chi2 = 48/57 dof).\n\nAll the quoted errors are at the 68% confidence level.\nAll the quoted values are preliminary. ",
  "format": "text/plain"
}