{
  "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 long-duration GRB 251230A / EP251230a\n(Swift-BAT detection: Lanava et al., GCN 43252;\nEinstein Probe-WXT detection: Wang et al., GCN 43259;\nWang et al., GCN 43272;\nInsight-HXMT/HE detection: Guo et al., GCN 43299;\nGECAM-B detection: Guo et al., GCN 43301)\ntriggered Konus-Wind at T0=04927.542 s UT (01:22:07.542).\n\nThe burst light curve shows a multipeaked structure\nwhich starts at ~T0-25 s and has a total duration of ~73 s.\nThe emission is seen up to ~2 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB251230_T04927/\n\nAs observed by Konus-Wind, the burst\nhad the total fluence of 2.03(-0.15,+0.17)x10^-5 erg/cm2,\nand the 64-ms peak flux, measured from T0-0.224 s,\nof 2.51(-0.71,+0.80)x10^-6 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+49.408 s)\nis best fit in the 20 keV - 10 MeV range\nby a power law with exponential cutoff model:\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nwith alpha = -1.04(-0.14,+0.16)\nand Ep = 354(-47,+64) keV (chi2 = 93/98 dof).\nFitting by a GRB (Band) model yields the same alpha and Ep,\nand an upper limit on the high energy photon index: beta < -2.2\n(chi2 = 93/97 dof).\n\nThe spectrum near the maximum count rate\n(measured from T0 to T0+0.256 s)\nis best fit in the 20 keV - 10 MeV range\nby a power law with exponential cutoff model:\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nwith alpha = -0.70(-0.51,+0.72)\nand Ep = 350(-85,+147) keV (chi2 = 19/15 dof).\nFitting by a GRB (Band) model yields the same alpha and Ep,\nand an upper limit on the high energy photon index: beta < -2.8\n(chi2 = 18/14 dof).\n\nAll the quoted errors are at the 68% confidence level.\nAll the quoted values are preliminary. ",
  "submittedHow": "web",
  "format": "text/plain",
  "subject": "Konus-Wind detection of GRB 251230A / EP251230a",
  "bibcode": "2026GCN.43405....1S",
  "submitter": "Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>",
  "createdOn": 1768418001389,
  "eventId": "GRB 251230A",
  "circularId": 43405
}