{
  "bibcode": "2022GCN.31936....1V",
  "body": "A. von Kienlin (MPE) and C. Meegan (UAH)\nreport on behalf of the Fermi GBM Team:\n\n\"At 08:17:54.53 UT on 21 April 2022, the Fermi Gamma-Ray Burst Monitor (GBM)\ntriggered and located GRB 220421A (trigger 672221879/220421346), which was\nalso \ndetected by the Swift/BAT-GUANO (Raman et al. 2022, GCN 31934)\n\nThe on-ground calculated location, using the GBM trigger\ndata, is RA = 74.4, DEC = 23.1 (J2000 degrees,\nequivalent to 04 h 57 m, 23 d 06 '), with a statistical uncertainty\nof 2.1 degrees (radius, 1-sigma containment,\nstatistical only; there is additionally a systematic\nerror which we have characterized as a core-plus-tail model, with 90% of\nGRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg\nsystematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).\n\nThe angle from the Fermi LAT boresight at the GBM trigger time is 59\ndegrees.\n\nThe GBM light curve shows a single pulse with a duration (T90) of about 6.4\ns (50-300 keV).\nThe time-averaged spectrum from T0+0.002 s to T0+7.008 s is best fit by a\nBand function \nwith Epeak = 133.20 +/- 5.40 keV, alpha = -0.41 +/- 0.05, and beta = -2.48\n+/- 0.11\n\nThe event fluence (10-1000 keV) in this time interval is\n(7.2 +/- 0.2)E-06. The 1.024-sec peak photon flux measured\nstarting from T0+1.056 s in the 10-1000 keV band\nis 13.2 +/- 0.3 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:\nhttps://fermi.gsfc.nasa.gov/ssc/data/access/gbm/\"",
  "circularId": 31936,
  "createdOn": 1650726453000,
  "email": "azk@mpe.mpg.de",
  "subject": "GRB 220421A: Fermi GBM observation",
  "submitter": "Andreas von Kienlin at MPE  <azk@mpe.mpg.de>",
  "eventId": "GRB 220421A"
}