{
  "bibcode": "2026GCN.43384....1P",
  "createdOn": 1768272716048,
  "submitter": "Eva MP at INAOE <eva.palafox@gmail.com>",
  "circularId": 43384,
  "format": "text/plain",
  "eventId": "GRB 260111A",
  "submittedHow": "web",
  "body": "Eva Palafox (INAOE) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 16:33:14.01 UT on 11 January 2026, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 260111A (trigger 789841999/260111690).\nwhich was also detected by Swift/BAT (S. Ronchini et al. 2026, GCN 43377).\nThe Fermi GBM on-ground location (GCN 43370) is consistent with the Swift/BAT position.\n\nThe angle from the Fermi LAT boresight is 14.4 degrees.\n\nThe GBM light curve consists of a single emission episode with a duration (T90)\nof about 31 s (50-300 keV). The time-averaged spectrum\nfrom T0-18 to T0+52 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -0.7 +/- 0.3 and the cutoff energy,\nparameterized as Epeak, is 140 +/- 30 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.3 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+0.70 s in the 10-1000 keV band is 2.4 +/- 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/\"\n",
  "subject": "GRB 260111A: Fermi GBM Observation"
}