{
  "createdOn": 1782392578092,
  "circularId": 45044,
  "format": "text/plain",
  "submitter": "Christian Malacaria at INAF-OAR <cmalacaria.astro@gmail.com>",
  "subject": "GRB 260618A: Fermi GBM Observation",
  "submittedHow": "web",
  "eventId": "GRB 260618A",
  "body": "C. Malacaria (INAF-OAR) and R. Sonawane (IISER, TVM) report \non behalf of the Fermi Gamma-ray Burst Monitor Team:\n\n\"At 06:45:34.28 UT on 18 June 2026, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 260618A (trigger 803457939/260618282).\nFinal Real-time localization was reported in GCN 44973.\nA possible afterglow is  detected by EP (Yang et al., GCN 44978, \nJiang et al., GCN 44991).\n\nThe GBM light curve consists of a variable emission episode with a duration (T90)\nof about 140 s (50-300 keV). The time-averaged spectrum\nfrom T0-17 to T0+150 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -1.4 +/- 0.1 and the cutoff energy, \nparameterized as Epeak, is 43 +/- 2 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(5.9 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+25 s in the 10-1000 keV band is 2.7 +/- 0.3 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/\""
}