{
  "createdOn": 1769808475659,
  "format": "text/plain",
  "subject": "GRB 260127B: Fermi GBM Detection",
  "circularId": 43573,
  "submittedHow": "web",
  "eventId": "GRB 260127B",
  "submitter": "atrigg2@lsu.edu",
  "bibcode": "2026GCN.43573....1T",
  "body": "A. C. Trigg (NPP ORAU, NASA MSFC) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:\n\n\"At 20:02:32.57 UT on 27 January 2026, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 260127B (trigger 791236957/260127835).\n\nThe on-ground calculated location, using the Fermi GBM trigger data,\nis RA = 190.42, Dec = 56.88 (J2000 degrees, equivalent to\nJ2000 12h 41m, +56d 52'), with a statistical uncertainty of 5.21 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 109 degrees.\n\nThe GBM light curve displays a single short peak with a duration (T90)\nof about 1 s (50-300 keV). The time-averaged spectrum\nfrom T0-0.1 to T0+0.3 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -0.11 +/- 0.01 and the cutoff energy,\nparameterized as Epeak, is 710 +/- 30 keV.\n\n\nThe event fluence (10-1000 keV) in this time interval is\n(1.29 +/- 0.09)E-06 erg/cm^2. The 64-ms peak photon flux measured\nstarting from T0+0.064 s in the 10-1000 keV band is 22 +/- 2 ph/s/cm^2.\n\nA Band function fits the spectrum equally well\nwith Epeak= 570 +/- 20 keV, alpha = -0.040 +/- 0.002 and beta = -2 +/- 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/\""
}