{
  "bibcode": "2019GCN.26506....1R",
  "body": "A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks,\nM. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline\non behalf of the Konus-Wind team, report:\n\nThe long-duration GRB 191218A (Swift-BAT trigger #944916:\nTroja et al., GCN 26480; Markwardt et al., GCN 26495;\nAstroSat CZTI detection: Gaikwad et al., GCN 26482)\ntriggered Konus-Wind at T0=9758.735 s UT (02:42:38.735).\n\nThe burst light curve shows a double-peaked structure\nwhich starts at ~T0-0.5 s and has a total duration of ~78.8 s.\nThe emission is seen up to ~4 MeV.\n\nAs observed by Konus-Wind, the burst\nhad a fluence of 3.92(-0.37,+0.45)x10^-5 erg/cm2,\nand a 64-ms peak flux, measured from T0+1.440 s,\nof 4.08(-1.07,+1.07)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+81.664 s)\nis best fit in the 20 keV - 4 MeV range\nby a power law with exponential cutoff model:\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nwith  alpha = -0.76(-0.18,+0.20)\nand Ep = 330(-44,+61) keV (chi2 = 54/69 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 = 53/68 dof).\n\nThe spectrum near the maximum count rate\n(measured from T0+0.256 to T0+7.936 s)\nis best fit in the 20 keV - 4 MeV range\nby a power law with exponential cutoff model\nwith  alpha = -0.27(-0.15,+0.17)\nand Ep = 322(-24,+28) keV (chi2 = 74/69 dof).\nFitting by a GRB (Band) model yields the same alpha and Ep,\nand an upper limit on the high energy photon index: beta < -2.7\n(chi2 = 73/68 dof).\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB191218_T09758/\n\nAll the quoted errors are at the 90% confidence level.\nAll the quoted values are preliminary.",
  "circularId": 26506,
  "createdOn": 1576785526000,
  "email": "ann_kozlova@mail.ioffe.ru",
  "subject": "Konus-Wind observation of GRB 191218A",
  "submitter": "Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>",
  "eventId": "GRB 191218A"
}