{
  "bibcode": "2025GCN.39680....1P",
  "submittedHow": "web",
  "submitter": "Utkarsh Pathak at IIT Bombay <utkarshpathak.07@gmail.com>",
  "circularId": 39680,
  "subject": "GRB 250228A: Fermi GBM Observation",
  "format": "text/plain",
  "body": "U. Pathak (IIT Bombay), M. Dafčíková (Masaryk U.), and C. Meegan (UAH) report \non behalf of the Fermi Gamma-ray Burst Monitor Team:\n\n\"At 07:23:46.16 UT on 28 February 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 250228A (trigger 762420231/250228308).\nwhich was also detected by Swift/BAT-GUANO (Ronchini et al. 2025, GCN 39674).\nThe Fermi GBM on-ground location is consistent with the Swift/BAT position.\n\nThe angle from the Fermi LAT boresight is 27 degrees.\n\nThe GBM light curve consists of a weak pulse from a single emission episode\nwith a duration (T90) of about 0.6 s (50-300 keV). The time-averaged spectrum\nfrom T0-0.5 to T0+0.3 s is best fit by\na simple power law function with index -1.45 +/- 0.1.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.0 +/- 0.3)E-07 erg/cm^2. The 64-ms peak photon flux measured\nstarting from T0-0.064 s in the 10-1000 keV band is 4.3 +/- 0.9 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 \nPage: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/\"",
  "createdOn": 1741763605790,
  "eventId": "GRB 250228A"
}