{
  "eventId": "GRB 250601A",
  "subject": "GRB 250601A: Fermi GBM Observation",
  "circularId": 40621,
  "submittedHow": "web",
  "submitter": "Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>",
  "bibcode": "2025GCN.40621....1S",
  "body": "V. Sharma (NASA-GSFC/UMBC) and C. Meegan (UAH) report on behalf of the \nFermi Gamma-ray Burst Monitor Team:\n\n\"At 17:29:35 UT on 1 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 250601A (trigger 770491780 / 250601729).\nwhich was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2025, GCN 40600) \nand Swift/XRT (K.L. Page et al. 2025, GCN 40604). \nThe Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position.\n\nThe angle from the Fermi LAT boresight is 24 degrees.\n\nThe GBM light curve consists of main emission episode with a \nduration (T90) of about 3 s (50-300 keV). The time-averaged \nspectrum from T0-0.5 to T0+2.4 s is best fit by a power law \nfunction with an exponential high-energy cutoff. The \npower law index is -0.58 +/- 0.1 and the cutoff energy, \nparameterized as Epeak, is 873 +/- 142 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.7 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+1 s in the 10-1000 keV band is 4.9 +/- 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 Page:\nhttps://fermi.gsfc.nasa.gov/ssc/data/access/gbm/\"",
  "format": "text/plain",
  "createdOn": 1748965336814
}