{
  "eventId": "GRB 260411B",
  "format": "text/plain",
  "subject": "GRB 260411B: Fermi GBM Detection",
  "createdOn": 1775915190448,
  "submitter": "Utkarsh Pathak at IIT Bombay <utkarshpathak.07@gmail.com>",
  "bibcode": "2026GCN.44266....1P",
  "body": "U. Pathak (IITB) and R. Sonawane (IISER TVM) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 08:04:35.31 UT on 11 April 2026, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 260411B (trigger 797587480/260411337).\nThe Fermi GBM final real-time Localization is reported in GCN 44262.\nAn optical counterpart is also detected by GOTO (O'Neill et al. 2026 GCN 44265).\n\nThe angle from the Fermi LAT boresight is 60 degrees.\n\nThe GBM light curve consists of two spikes in a single emission episode, with a duration (T90)\nof about 33 s (50-300 keV). The time-averaged spectrum\nfrom T0-2.9 to T0+29.2 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -0.62 +/- 0.02 and the cutoff energy,\nparameterized as Epeak, is 348 +/- 4 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.31 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+8.3 s in the 10-1000 keV band is 21.8 +/- 0.4 ph/s/cm^2.\n\nA Band function fits the spectrum equally well\nwith Epeak= 293 +/- 3 keV, alpha = -0.54 +/- 0.05 and beta = -2.3 +/- 0.1.\n\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/\"",
  "circularId": 44266,
  "submittedHow": "web"
}