{
  "bibcode": "2017GCN.21777....1B",
  "body": "E. Bissaldi (Politecnico & INFN Bari)\nreports on behalf of the Fermi GBM Team:\n\n\n\"At 04:18:11.13 UT on 31 August 2017, the Fermi Gamma-Ray Burst Monitor\ntriggered and located GRB 170831A (trigger 525845896 / 170831179).\n\nThe on-ground calculated location, using the GBM trigger\ndata, is\n\nRA = 158.7, DEC = +49.8\n\n(J2000 degrees, equivalent to 10h 34m, 49d 48'), with an uncertainty\nof 1.6 degrees (radius, 1-sigma containment,\nstatistical only; there is additionally a systematic\nerror which we have characterized as a core-plus-tail model, with 90% of\nGRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg\nsystematic error. [Connaughton et al. 2015, ApJS, 216, 32]).\n\nThe trigger resulted in an Autonomous Repoint Request (ARR)\nby the GBM Flight Software owing to the high peak flux\nof the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight\nlocation. The initial angle from the Fermi LAT boresight to\nthe GBM ground location is 43 degrees.\n\nThe GBM light curve consists of multiple peaks\nwith a duration (T90) of about 60 s (50-300 keV).\nThe time-averaged spectrum from T0-1.5 s to T0+55 s is\nadequately fit by a Band function with Epeak = 90 +/- 5 keV,\nalpha = -1.32 +/- 0.03, and beta = -2.52 +/- 0.12.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.03 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+44 s in the 10-1000 keV band\nis 23.8 +/- 0.4 ph/s/cm^2.\n\n\nThe spectral analysis results presented above are preliminary;\nfinal results will be published in the GBM GRB Catalog.\"",
  "circularId": 21777,
  "createdOn": 1504199123000,
  "email": "Elisabetta.Bissaldi@uibk.ac.at",
  "subject": "GRB 170831A: Fermi GBM detection",
  "submitter": "Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>",
  "eventId": "GRB 170831A"
}