{
  "bibcode": "2025GCN.40633....1G",
  "circularId": 40633,
  "eventId": "GRB 250605A",
  "subject": "GRB 250605A: Swift detection of a burst",
  "submitter": "K.L. Page at U Leicester <klp5@leicester.ac.uk>",
  "createdOn": 1749150483294,
  "body": "R. Gupta (NASA GSFC), J. J. DeLaunay (PSU), S. Dichiara (PSU),\nC. Gronwall (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),\nH. A. Krimm (NSF), M. J. Moss (GSFC), K. L. Page (U Leicester),\nT. M. Parsotan (GSFC), M. H. Siegel (PSU) and M. A. Williams (PSU)\nreport on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 18:52:31.27 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 250605A (trigger=1321323).  Swift slewed immediately to the burst.\nThe BAT on-board calculated location is \nRA, Dec 166.977, -19.795 which is \n   RA(J2000) = 11h 07m 54s\n   Dec(J2000) = -19d 47' 42\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a complex light curve \nwith one strong pulse between T0-2 sec to T0+10 sec and a second dimmer but \nbroad pulse between T0+40 sec to T0+100 sec.  The peak count rate was 4,000\n counts/sec (15-350 keV), at ~2 sec after the trigger.\n\nThe XRT began observing the field at 18:54:09.2 UT, 98.0 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 166.9571, -19.7882 which is equivalent to:\n   RA(J2000)  = 11h 07m 49.70s\n   Dec(J2000) = -19d 47' 17.5\"\nwith an uncertainty of 5.5 arcseconds (radius, 90% containment). This\nlocation is 71 arcseconds from the BAT onboard position, within the BAT\nerror circle. No event data are yet available to determine the column\ndensity using X-ray spectroscopy.\n\nUVOT took a finding chart exposure of 144 seconds with the White filter\nstarting 106 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 100% of\nthe XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.\nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.039.\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",
  "submittedHow": "email"
}