{
  "bibcode": "2023GCN.33146....1L",
  "body": "S. Lesage (UAH) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 21:46:05 UT on 31 December 2022, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 221231A (trigger 694215970/221231907).\nwhich was also detected by Swift BAT (A. Tohuvavohu et al. 2023, GCN 33132)\nand Swift XRT GCN (M. Perri et al. 2023, 33139).\nThe Fermi GBM on-ground location is consistent with the Swift position.\n\nThe angle from the Fermi LAT boresight is 61 degrees.\n\nThe GBM light curve consists of a single emission episode with a duration\n(T90)\nof about 5 s (50-300 keV). The time-averaged spectrum\nfrom T0-0.06 to T0+4.93 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -0.2 +/- 0.4 and the cutoff energy,\nparameterized as Epeak, is 200 +/- 40 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(4.4 +/- 0.4)E-07 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+0 s in the 10-1000 keV band is 3.9 +/- 0.2 ph/s/cm^2.\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\nPage:\nhttps://fermi.gsfc.nasa.gov/ssc/data/access/gbm/\"",
  "circularId": 33146,
  "createdOn": 1672808514000,
  "email": "sjl0014@uah.edu",
  "subject": "GRB 221231A: Fermi GBM Observation",
  "submitter": "Stephen Lesage at Fermi-GBM Team  <sjl0014@uah.edu>",
  "eventId": "GRB 221231A"
}