{
  "bibcode": "2024GCN.37956....1K",
  "circularId": 37956,
  "createdOn": 1730268342046,
  "eventId": "GRB 241030A",
  "subject": "GRB 241030A: Swift detection of a burst with a bright optical counterpart",
  "submitter": "Simone Dichiara at Pennsylvania State University <sbd5667@psu.edu>",
  "submittedHow": "email",
  "body": "N. J. Klingler (GSFC/UMBC/CRESSTII), S. Dichiara (PSU),\nR. Gupta (NASA GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU)\nreport on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 05:48:03 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 241030A (trigger=1263718).  Swift slewed immediately to the burst.\nThe BAT on-board calculated location is \nRA, Dec 343.033, +80.439 which is \n   RA(J2000) = 22h 52m 08s\n   Dec(J2000) = +80d 26' 20\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a complex\nstructure with a duration of at least 180 sec.  The peak count rate\nwas ~12000 counts/sec (15-350 keV), at ~162 sec after the trigger.\n\nThe XRT began observing the field at 05:49:16.6 UT, 73.5 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 343.1400, 80.4482 which is equivalent to:\n   RA(J2000)  = 22h 52m 33.60s\n   Dec(J2000) = +80d 26' 53.5\"\nwith an uncertainty of 4.7 arcseconds (radius, 90% containment). This\nlocation is 72 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 150 seconds with the White filter\nstarting 82 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t22:52:33.57 = 343.13987\n  DEC(J2000) = +80:26:59.9  =  80.44996\nwith a 90%-confidence error radius of about 0.61 arc sec. This position is 6.3\narc sec. from the center of the XRT error circle. The estimated magnitude is\n15.42 with a 1-sigma error of about  0.14. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.131.\n\nBurst Advocate for this burst is N. J. Klingler (noelklin AT umbc.edu).\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"
}