{
  "bibcode": "2017GCN.21966....1C",
  "body": "S. B. Cenko (GSFC), S. D. Barthelmy (GSFC),\nA. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL),\nP. A. Evans (U Leicester), J.D. Gropp (PSU), K. L. Page (U Leicester)\nand M. H. Siegel (PSU) report on behalf of the Swift Team:\n\nAt 07:55:32 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 171004A (trigger=776347).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 139.162, +52.680, which is \n   RA(J2000)  =  09h 16m 39s\n   Dec(J2000) = +52d 40' 48\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for image triggers, there is nothing\nsignificant in the real-time light curve. \n\nThe XRT began observing the field at 07:58:26.9 UT, 174.7 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 139.1713, 52.6937 which is equivalent to:\n   RA(J2000)  = +09h 16m 41.11s\n   Dec(J2000) = +52d 41' 37.3\"\nwith an uncertainty of 4.9 arcseconds (radius, 90% containment). This\nlocation is 53 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 3.22e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of  52 seconds with the White filter\nstarting 184 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\n0.02. \n\nBurst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). \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": 21966,
  "createdOn": 1507105231000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 171004A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 171004A"
}