{
  "bibcode": "2017GCN.21106....1U",
  "body": "T. N. Ukwatta (LANL), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC)\nand K. L. Page (U Leicester) report on behalf of the Swift Team:\n\nAt 05:10:02 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 170519A (trigger=753445).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 163.450, +25.378 which is \n   RA(J2000) = 10h 53m 48s\n   Dec(J2000) = +25d 22' 41\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single-peaked\nstructure with a duration of about 10 sec.  The peak count rate\nwas ~1500 counts/sec (15-350 keV), at ~3 sec after the trigger. \n\nThe XRT began observing the field at 05:11:23.2 UT, 80.4 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 163.42823, 25.37377 which\nis equivalent to:\n   RA(J2000)  = 10h 53m 42.78s\n   Dec(J2000) = +25d 22' 25.6\"\nwith an uncertainty of 4.8 arcseconds (radius, 90% containment). This\nlocation is 72 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 http://www.swift.ac.uk/sper.  We\ncannot determine whether the source is fading at the present time. 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 3.58e-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 91 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t10:53:42.46 = 163.42693\n  DEC(J2000) = +25:22:27.4  =  25.37429\nwith a 90%-confidence error radius of about 0.75 arc sec. This position is 1.4\narc sec. from the center of the XRT error circle. The estimated magnitude is\n17.07 with a 1-sigma error of about  0.14. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.03. \n\nBurst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta 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": 21106,
  "createdOn": 1495171457000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 170519A: Swift detection of a burst with an optical counterpart",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 170519A"
}