{
  "bibcode": "2023GCN.34670....1S",
  "circularId": 34670,
  "submitter": "Lorenzo Scotton at UAH <lscottongcn@outlook.com>",
  "createdOn": 1694472314761,
  "subject": "GRB 230911D: Fermi GBM observation",
  "submittedHow": "web",
  "body": "L. Scotton (UAH), R. Hamburg (CNRS/IJCLab), and C. Meegan (UAH)\nreport on behalf of the Fermi GBM Team:\n\n\"At 07:53:09.72 UT on 11 September 2023, the Fermi Gamma-Ray Burst Monitor (GBM)\ntriggered and located GRB 230911D (trigger 716111594 / 230911329),\nwhich was also detected by the Fermi LAT (F. Longo et al. 2023, GCN 34668) \nand Konus-Wind (D. Frederiks et al. 2023, GCN 34659).\n\nThe Fermi GBM Final Localization (GCN 34656) is consistent with the Fermi LAT position.\n\nThe angle from the Fermi LAT boresight at the GBM trigger time is 72 degrees.\n\nThe GBM light curve consists of multiple peaks\nwith a duration (T90) of about 45.6 s (50-300 keV).\nThe time-averaged spectrum from T0-4.4 s to T0+77.6 s is\nbest fit by a power law function with an exponential\nhigh-energy cutoff.  The power law index is -1.00 +/- 0.01 and\nthe cutoff energy, parameterized as Epeak, is 429.9 +/- 7.8 keV\n\nThe event fluence (10-1000 keV) in this time interval is \n(1.214 +/- 0.007)E-04 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+16.1 s in the 10-1000 keV band\nis 24.8 +/- 0.3 ph/s/cm^2.\n\nA Band function fits the spectrum equally well\nwith Epeak= 420.6 +/- 9.0 keV, alpha = -1.00 +/- 0.01 and beta = -3.02 +/- 0.25.\n\nThe spectral analysis results presented above are preliminary;\nfinal results will be published in the GBM GRB Catalog:\nhttps://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html\n\nFor Fermi GBM data and info, please visit the official Fermi GBM Support Page:\nhttps://fermi.gsfc.nasa.gov/ssc/data/access/gbm/\"",
  "eventId": "GRB 230911D"
}