{
  "submittedHow": "email",
  "eventId": "GRB 240511A",
  "bibcode": "2024GCN.36430....1L",
  "body": "\nS. Laha (GSFC/UMBC), A. D'Ai (INAF-IASFPA),\nV. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), R. Gupta (NASA/GSFC),\nJ. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa),\nD. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the\nNeil Gehrels Swift Observatory Team:\n\nAt 18:06:53 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 240511A (trigger=1227767).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 336.664, +8.514 which is \n   RA(J2000) = 22h 26m 39s\n   Dec(J2000) = +08d 30' 49\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed multi-peaked\nstructure with a duration of about 100 sec.  The peak count rate\nwas ~ 4600 counts/sec (15-350 keV), at ~20 sec after the trigger. \n\nThe XRT began observing the field at 18:08:36.4 UT, 103.2 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nfading, uncatalogued X-ray source located at RA, Dec 336.67568, 8.51315\nwhich is equivalent to:\n   RA(J2000)  = 22h 26m 42.16s\n   Dec(J2000) = +08d 30' 47.3\"\nwith an uncertainty of 4.2 arcseconds (radius, 90% containment). This\nlocation is 41 arcseconds from the BAT onboard position, within the BAT\nerror circle. This position may be improved as more data are received;\nthe latest position is available at https://www.swift.ac.uk/sper. No\nspectrum from the promptly downlinked event data is yet available to\ndetermine the column density. \n\nThe initial flux in the 2.5 s image was 3.70e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 110 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\n0.098. \n\nBurst Advocate for this burst is S. Laha (sib.laha 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",
  "createdOn": 1715451733607,
  "circularId": 36430,
  "subject": "GRB 240511A: Swift detection of a burst",
  "submitter": "David Palmer at LANL <palmer@lanl.gov>"
}