{
  "subject": "GRB 260429A: Fermi GBM Detection",
  "eventId": "GRB 260429A",
  "circularId": 44430,
  "submittedHow": "web",
  "createdOn": 1777533023529,
  "submitter": "Lorenzo Scotton at UAH <lscottongcn@outlook.com>",
  "format": "text/plain",
  "body": "L. Scotton (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:\n\n\"At 23:24:02.02 UT on 29 April 2026, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 260429A (trigger 799197847/260429975).\n\nThe on-ground calculated location, using the Fermi GBM trigger data,\nis RA = 283.92, Dec = 18.10 (J2000 degrees, equivalent to\nJ2000 18h 55m, +18d 6'), with a statistical uncertainty of 2.61 degrees.\n(radius, 1-sigma containment, statistical only; there is additionally a\nsystematic error which we have characterized as a mixture of two Gaussians,\none with a radius of 1.8 degrees (52% contribution) and one with a radius\nof 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]).\n\nThe angle from the Fermi LAT boresight is 76 degrees.\n\nThe GBM light curve consists of a single emission episode with a duration (T90)\nof about 0.16 s (50-300 keV). The time-averaged spectrum\nfrom T0-0.1 to T0+0.4 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -1 +/- 0.04 and the cutoff energy,\nparameterized as Epeak, is 900 +/- 20 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.41 +/- 0.07)E-06 erg/cm^2. The 64-ms peak photon flux measured\nstarting from T0+0.0 s in the 10-1000 keV band is 69 +/- 2 ph/s/cm^2.\n\nA Band function fits the spectrum equally well\nwith Epeak= 600 +/- 20 keV, alpha = -0.92 +/- 0.03 and beta = -2 +/- 0.09.\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/\""
}