{
  "createdOn": 1736558767659,
  "subject": "GRB 250101B: Fermi GBM Observation",
  "bibcode": "2025GCN.38903....1M",
  "submitter": "oindabimukherjee@gmail.com",
  "format": "text/plain",
  "body": "O. Mukherjee (USRA), S. Bala (USRA) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 23:14:12.65 UT on 01 January 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 250101B (trigger 757466057/250101968).\nwhich was also detected by SVOM/GRM (Zhang et al. 2025, GCN 38793).\n\nThe on-ground calculated location, using the Fermi GBM trigger data,\nis RA = 70.87, Dec = -3.25 (J2000 degrees, equivalent to\nJ2000 4h 43m, -3d 15'), with a statistical uncertainty of 3.29 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 49 degrees.\n\nThe GBM light curve consists of a single emission episode with two distinct peaks with a duration (T90)\nof about 4.5 s (50-300 keV). The time-averaged spectrum\nfrom T0-1.0 to T0+5.1 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -0.34 +/- 0.09 and the cutoff energy,\nparameterized as Epeak, is 146 +/- 7 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.418 +/- 0.8)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+0.77 s in the 10-1000 keV band is 5 +/- 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/\"",
  "circularId": 38903,
  "eventId": "GRB 250101B",
  "submittedHow": "web"
}