{
  "createdOn": 1716427272477,
  "submitter": "Sarah Dalessi at UAH <sd0104@uah.edu>",
  "circularId": 36535,
  "submittedHow": "web",
  "bibcode": "2024GCN.36535....1D",
  "format": "text/plain",
  "subject": "GRB 240521B: Fermi GBM Observation",
  "body": "S. Dalessi (UAH), C. Fletcher (USRA), and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 15:08:57.06 UT on 21 May 2024, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 240521B (trigger 737996942/240521631).\nwhich was also detected by Swift/BAT-GUANO (Ronchini et al. 2024, GCN 36532).\nThe Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position.\n\nThe angle from the Fermi LAT boresight is 101 degrees.\n\nThe GBM light curve single emission episode with a duration (T90)\nof about 34 s (50-300 keV). The time-averaged spectrum\nfrom T0-16 to T0+17 s is best fit by\na simple power law function with index -1.64 +/- 0.04.\n\nThe event fluence (10-1000 keV) in this time interval is\n(4 +/- 0.5)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0-9.9 s in the 10-1000 keV band is 4.1 +/- 0.4 ph/s/cm^2.\n\nA power law function with an exponential high-energy cutoff fits the spectrum equally well. The power law index is -1.48 +/- 0.11 and the cutoff energy,\nparameterized as Epeak, is 222 +/- 94 keV.\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 240521B"
}