{
  "eventId": "GRB 250321A",
  "bibcode": "2025GCN.39794....1G",
  "submitter": "David Palmer at LANL <palmer@lanl.gov>",
  "body": "R. Gupta (NASA GSFC), J. A. Kennea (PSU),\nN. J. Klingler (GSFC/UMBC/CRESSTII), D. M. Palmer (LANL) and\nM. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 00:42:38 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 250321A (trigger=1297508).  Swift slewed immediately to the burst.\nThe BAT on-board calculated location is \nRA, Dec 295.077, +21.041 which is \n   RA(J2000) = 19h 40m 19s\n   Dec(J2000) = +21d 02' 27\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  Only the first 8 seconds of the BAT light\ncurve after the trigger is available due to a telemetry gap.\nThis data shows a complex structure with a duration of\nat least 10 sec.  The peak count rate was ~2500 counts/sec (15-350 keV),\nat ~0 sec after the trigger.\n\nThe XRT began observing the field at 00:44:43.60 UT, 125.6 seconds after\nthe BAT trigger. No source was detected in the 2.5-s promptly available\nimage. We are waiting for the full dataset to detect and localise the\nXRT counterpart.\n\nDue to a telemetry gap, UVOT data are not available at this time.\n\nAlthough XRT did not report an X-ray counterpart in the limited immediately\ntransmitted data, the significance of the BAT image (>10 sigma), the\nshape of the BAT light curve, and the simultaneous detection by Fermi/GBM\n(trigger 764210564) give us confidence that this is an astrophysical\nGamma Ray Burst.\n\nBurst Advocate for this burst is R. Gupta (rahulbhu.c157 AT gmail.com).\nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/)\n\n",
  "circularId": 39794,
  "subject": "GRB 250321A: Swift detection of a burst",
  "createdOn": 1742519062394,
  "submittedHow": "email"
}