{
  "bibcode": "2017GCN.22053....1D",
  "body": "P. D'Avanzo (INAF-OAB), P. A. Evans (U Leicester),\nN. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester),\nD. M. Palmer (LANL) and B. Sbarufatti (PSU) report on behalf of the\nSwift Team:\n\nAt 08:23:06 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 171027A (trigger=783479).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 61.680, -2.606 which is \n   RA(J2000) = 04h 06m 43s\n   Dec(J2000) = -02d 36' 21\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a multiple-peaked\nstructure with a duration of about 120 sec.  The peak count rate\nwas ~4000 counts/sec (15-350 keV), at ~60 sec after the trigger. \n\nThe XRT began observing the field at 08:24:34.1 UT, 87.6 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nfading, uncatalogued X-ray source located at RA, Dec 61.68989, -2.62100\nwhich is equivalent to:\n   RA(J2000)  = 04h 06m 45.57s\n   Dec(J2000) = -02d 37' 15.6\"\nwith an uncertainty of 3.6 arcseconds (radius, 90% containment). This\nlocation is 64 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (1.08 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 2.9\n(+2.47/-2.17) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 2.5 s image was 1.36e-08 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 95 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\n0.14. \n\nBurst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it). \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": 22053,
  "createdOn": 1509093601000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 171027A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 171027A"
}