{
  "bibcode": "2009GCN..9861....1G",
  "body": "S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,\nP. Oleynik, M. Ulanov, D. Svinkin, and T. Cline\non behalf of the Konus-Wind team, report:\n\nGRB 090831A (Rau, GCN 9850; Matsuoka et al., GCN 9852)\ntriggered Konus-Wind at T0=27393.820 s UT (07:36:33.820)\n\nThe burst started with a short (~250 ms) spike which resembles\na classical short/hard GRB. The spike is followed by a structured\nprofile with a total duration of ~50 s.\nThe Konus-Wind light curves of this GRB are available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB090831_T27393/\n\nAs observed by Konus-Wind, the burst had\na fluence of 1.33(-0.2,+0.25)x10-5 erg/cm2, and\na 16-ms peak flux, measured from T0,\nof 9.3(-2.2,+3.2)x10-6 erg/cm2/s\n(both in the 20 keV - 2 MeV energy range).\n\nThe time-integrated spectrum of the burst (from T0 to T0+49.408 s)\nis well fitted (in the 20 keV - 2 MeV range)\nby a power law with exponential cutoff model:\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with\nalpha = -1.53(-0.14,+0.16),  and\nEp = 253(-69,+162)keV (chi2 = 69/61 dof).\nFitting by the GRB (Band) model yields to the same alpha and Ep\nvalues with the high energy photon index beta of -9 (< -2.1)\n\nThe spectrum at the maximum count rate,\nmeasured from T0 to T0 + 0.256s  (initial short pulse),\nis well fitted (in the 20 keV - 2 MeV range)\nby the GRB (Band) model with:\nalpha = -1.28(-0.3,+0.7),\nbeta  = -2.5( < -1.7), and\nEp    = 273(-212,+331)keV (chi2 = 12/22 dof).\n\nAll the quoted values are preliminary.\nAll the quoted errors are at the 90% confidence level.",
  "circularId": 9861,
  "createdOn": 1251812448000,
  "email": "fred@mail.ioffe.ru",
  "subject": "Konus-Wind observations of GRB 090831A",
  "submitter": "Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>",
  "eventId": "GRB 090831A"
}