{
  "circularId": 36416,
  "eventId": "GRB 240504A",
  "subject": "GRB 240504A: Fermi GBM Observation",
  "submitter": "Bagrat Mailyan at Florida Tech <mbagrat@gmail.com>",
  "createdOn": 1715193691192,
  "submittedHow": "web",
  "bibcode": "2024GCN.36416....1M",
  "body": "B. Mailyan (Florida tech) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 05:12:52.64 UT on 04 May 2024, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 240504A (trigger 736492377/240504217).\nwhich was also detected by Swift/BAT-GUANO (S. Ronchini et al. 2024, GCN 36401).\nThe Fermi GBM on-ground location is consistent with the Fermi GBM final position notice (GCN 36387).\n\nThe angle from the Fermi LAT boresight is 64 degrees.\n\nThe GBM light curve consists of a single emission episode with a duration (T90)\nof about 19 s (50-300 keV). The time-averaged spectrum\nfrom T0+0.003 to T0+20.096 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -1.12 +/- 0.02 and the cutoff energy,\nparameterized as Epeak, is 682.50 +/- 52.10. \nA Band function with Epeak 665.80 +/- 55.40, Alpha -1.11 +/- 0.02, Beta -3.01 +/- 0.77 fits the spectrum equally well. \n\nThe event fluence (10-1000 keV) in this time interval is\n(2.26 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+6.7 s in the 10-1000 keV band is 11.5 +/- 0.3 ph/s/cm^2.\n\nWe note that there is a second FRED-like peak about 100s after the reported event here that seems to be related. \nHowever, due to a contemporaneous solar flare, we are unable to disentangle the two events and thus we omit this \nportion of the burst due to contamination. We note that the burst could have a T90 of 250s, but other instruments are required to confirm this.\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/\""
}