{
  "bibcode": "2017GCN.21170....1E",
  "body": "P.A. Evans (U Leicester), S. D. Barthelmy (GSFC),\nH. A. Krimm (NSF/USRA), N. P. M. Kuin (UCL-MSSL),\nA. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),\nK. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and\nT. N. Ukwatta (LANL) report on behalf of the Swift Team:\n\nAt 20:07:32 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 170531A (trigger=755343).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 121.261, -14.033 which is \n   RA(J2000)  =  08h 05m 03s\n   Dec(J2000) = -14d 01' 57\"\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.  We note that this trigger occurred\nwhile coming out of the SAA. \n\nThe XRT began observing the field at 20:09:35.5 UT, 122.6 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 121.25380, -14.02292 which\nis equivalent to:\n   RA(J2000)  = 08h 05m 00.91s\n   Dec(J2000) = -14d 01' 22.5\"\nwith an uncertainty of 4.5 arcseconds (radius, 90% containment). This\nlocation is 44 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 2.92e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nNo UVOT data are available at this time. \n\nBurst Advocate for this burst is P.A. Evans (pae9 AT star.le.ac.uk). \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": 21170,
  "createdOn": 1496262824000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 170531A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 170531A"
}