{
  "bibcode": "2017GCN.22133....1T",
  "body": "A. Tohuvavohu (PSU), A. D'Ai (INAF-IASFPA), A. Deich (PSU),\nP. A. Evans (U Leicester), J.D. Gropp (PSU), A. Y. Lien (GSFC/UMBC)\nand K. L. Page (U Leicester) report on behalf of the Swift Team:\n\nAt 13:20:02 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 171120A (trigger=791201).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 163.787, +22.450 which is \n   RA(J2000) = 10h 55m 09s\n   Dec(J2000) = +22d 26' 58\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a multi-peaked\nstructure with a duration of about 60 sec.  The peak count rate\nwas ~17000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 13:21:31.0 UT, 88.5 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source with an enhanced position: RA, Dec 163.7911,\n22.4584 which is equivalent to:\n   RA(J2000)  = 10h 55m 09.87s\n   Dec(J2000) = +22d 27' 30.3\"\nwith an uncertainty of 2.5 arcseconds (radius, 90% containment). This\nlocation is 33 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata does not constrain the column density. \n\nThe initial flux in the 2.5 s image was 2.00e-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 98 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 A. Tohuvavohu (aaronb AT swift.psu.edu). \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": 22133,
  "createdOn": 1511184897000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 171120A: Swift detection of a burst",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 171120A"
}