{
  "bibcode": "2009GCN.10115....1M",
  "body": "S. McBreen (UCD/MPE) and V. Chaplin (UAH)\nreport on behalf of the Fermi GBM Team:\n\n\"At 12:00:28.85 UT on 31 October 2009, the Fermi Gamma-Ray Burst Monitor\ntriggered and located GRB 091031 (trigger 278683230 / 091031500).\n\nThe on-ground calculated location, using the GBM trigger\ndata, is RA = 70.6, DEC = -59.1 (J2000 degrees,\nequivalent to 04 h 42 m, -59 d 06 '), with an uncertainty\nof 1 degrees (radius, 1-sigma containment,\nstatistical only; there is additionally a systematic\nerror which is currently estimated to be 2 to 3 degrees).\nThe angle from the Fermi LAT boresight is 22 degrees.\n\nThe GBM light curve consists of a number of pulses with\nsub-structure and has a duration (T90) of about 35 s (8-1000 keV).\nThe time-averaged spectrum from T0-0.003 s to T0+36.609 s is\nbest fit by a Band function with Epeak = 503.10 (+47.30/-46.60) keV,\nalpha = -0.91 +/- 0.04, and beta = -2.34 (+0.19/-0.31)\n(CSTAT 674 for 602 d.o.f.).\n\nThe event fluence (8-1000 keV) in this time interval is\n(2.05 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+6.9 s in the 8-1000 keV band\nis 7.5 +/- 0.3 ph/s/cm^2.\n\nThe spectral analysis results presented above are preliminary;\nfinal results will be published in the GBM GRB Catalog.\"\n\n[GCN OPS NOTE(01nov09): Per author's request, the missing minus sign\nto the value for alpha was added.]",
  "circularId": 10115,
  "createdOn": 1257097010000,
  "email": "smcbreen@mpe.mpg.de",
  "subject": "GRB 091031: Fermi GBM detection",
  "submitter": "Sheila McBreen at MPE  <smcbreen@mpe.mpg.de>",
  "eventId": "GRB 091031"
}