{
  "eventId": "GRB 260604C",
  "createdOn": 1780627772958,
  "format": "text/plain",
  "body": "E. Neights (GWU, NASA GSFC) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 20:18:44.41 UT on 04 June 2026, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 260604C (trigger 802297129/260604846),\nwhich was also detected by SVOM ECLAIRs (Gotz et al. 2026, GCN 44823), \nMASTER (Lipunov et al. 2026, GCN 44827), and LAST (Konno et al. 2026, GCN 44828).\nThe Fermi GBM on-ground location is consistent with the SVOM ECLAIRs position.\n\nThe angle from the Fermi LAT boresight is 102 degrees.\n\nThe GBM light curve consists of a single emission episode with a duration (T90)\nof about 6.4 s (50-300 keV). The time-averaged spectrum\nfrom T0-2.2 to T0+12.0 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -1.03 +/- 0.01 and the cutoff energy,\nparameterized as Epeak, is 551 +/- 2 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.55 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+4.5 s in the 10-1000 keV band is 44.1 +/- 0.6 ph/s/cm^2.\n\nA Band function fits the spectrum equally well\nwith Epeak= 394 +/- 3 keV, alpha = -0.95 +/- 0.01 and beta = -2 +/- 0.03.\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/\"",
  "subject": "GRB 260604C: Fermi GBM Observation",
  "circularId": 44831,
  "submittedHow": "web",
  "submitter": "eliza.neights@gmail.com"
}