{
  "bibcode": "2018GCN.23263....1R",
  "body": "O.J. Roberts (USRA) and C. Meegan (UAH) and report \non behalf of the Fermi GBM Team:\n\n\"At 22:20:30.53 UT on 23 September 2018, the Fermi \nGamma-Ray Burst Monitor triggered and located \nGRB 180923B (trigger 559434035 / 180923931).\nThe on-ground calculated location, using the GBM trigger\ndata, is\n\nRA, Dec = 310.6, -0.7 (J2000 degrees)\n\nwith an uncertainty of 1.0 degree (radius, 1-sigma containment,\nstatistical only; there is additionally a systematic error which we \nhave characterized as a core-plus-tail model, with 90% of GRBs \nhaving 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 initial angle from the Fermi LAT boresight to\nthe best location is 86 degrees.\n\nThe GBM light curve shows/consists of two bright peaks\nwith a duration (T90) of about 8.2 s (50-300 keV).\nThe time-averaged spectrum from T0+0 s to T0+8.9 s is\nbest fit by a Band function with Epeak = 44.5 +/- 0.5,\nalpha index = -0.77 +/- 0.03 and beta index = -3.02 +/- 0.05.\n\nThe event fluence (10-1000 keV) in this time interval is\n(1.880 +/- 0.003)E-05 erg/cm^2. The 1s peak photon flux \nmeasured starting from T0+4.0 s in the 10-1000 keV band\nis 53 +/- 1 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(24sep18): Based on CIrcular 23265, the name\nof the GRB used in this circular (23263) was changed\nfrom \"180923A\" to \"180923B\".]",
  "circularId": 23263,
  "createdOn": 1537818716000,
  "email": "oliver.roberts@nasa.gov",
  "subject": "GRB 180923B: Fermi GBM detection",
  "submitter": "Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>",
  "eventId": "GRB 180923B"
}