{
  "bibcode": "2018GCN.22790....1L",
  "body": "S. J. LaPorte (PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU),\nA. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),\nD. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report\non behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 00:43:13 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 180618A (trigger=842475).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 169.937, +73.848 which is \n   RA(J2000) = 11h 19m 45s\n   Dec(J2000) = +73d 50' 52\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single FRED\nstructure with a duration of about 20 sec.  The peak count rate\nwas ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 00:44:30.5 UT, 77.6 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 169.9415, 73.8358 which is equivalent to:\n   RA(J2000)  = +11h 19m 45.96s\n   Dec(J2000) = +73d 50' 08.9\"\nwith an uncertainty of 5.4 arcseconds (radius, 90% containment). This\nlocation is 44 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\nThe initial flux in the 2.5 s image was 1.27e-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 86 seconds after the BAT trigger. There is a candidate afterglow in\nthe list of sources generated on-board at\n  RA(J2000)  =\t11:19:45.78 = 169.94074\n  DEC(J2000) = +73:50:13.3  =  73.83704\nwith a 90%-confidence error radius of about 1.10 arc sec. This position is 4.5\narc sec. from the center of the XRT error circle. The estimated magnitude is\n17.81. No correction has been made for the expected extinction corresponding to\nE(B-V) of 0.07. \n\nBurst Advocate for this burst is S. J. LaPorte (extragsam 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/too.html.)",
  "circularId": 22790,
  "createdOn": 1529283233000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 180618A: Swift detection of a burst with an optical counterpart",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 180618A"
}