{
  "bibcode": "2021GCN.31202....1D",
  "body": "A. D'Ai (INAF-IASFPA), E. Ambrosi (INAF-IASFPA),\nV. D'Elia (SSDC & INAF-OAR), J.D. Gropp (PSU), J. A. Kennea (PSU),\nN. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa),\nF. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),\nD. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII) and\nB. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 13:09:59 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 211211A (trigger=1088940).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 212.272,  +27.884d which is \n   RA(J2000) = 14h 09m 05s\n   Dec(J2000) = +27d 53' 01\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  Due to a telemetry dropout, the immediately\navailable BAT lightcurve starts at T+8s, and shows a bright complex\nburst that extends at least to T+100s.  At T+8s the count rate is \n300k counts/sec (15-350 keV), but the earlier peak may be significantly\nhigher. \n\nThe XRT began observing the field at 13:11:18.7 UT, 79.2 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 212.2912, 27.8899 which is equivalent to:\n   RA(J2000)  = 14h 09m 9.89s\n   Dec(J2000) = +27d 53' 23.6\"\nwith an uncertainty of 5.0 arcseconds (radius, 90% containment). This\nlocation is 64 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 nominal 150.000 seconds with the White\nfilter starting 87 seconds after the BAT trigger. No credible afterglow\ncandidate has been found in the initial data products. Data from the 2.7'x2.7'\nsub-image are not available at this time. The 8'x8' region for the list of\nsources generated on-board covers 100% of the XRT error circle. The list of\nsources is typically complete to about 18 mag. No correction has been made for\nthe expected extinction corresponding to E(B-V) of 0.018. \n\nBurst Advocate for this burst is A. D'Ai (antonino.dai AT inaf.it). \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/)",
  "circularId": 31202,
  "createdOn": 1639229577000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 211211A: Swift detection of a bright burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 211211A"
}