{
  "bibcode": "2016GCN.19098....1S",
  "body": "M. H. Siegel (PSU), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC),\nN. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC),\nL. M. McCauley (PSU), D. M. Palmer (LANL),\nB. Sbarufatti (INAF-OAB/PSU) and T. N. Ukwatta (LANL) report on behalf\nof the Swift Team:\n\nAt 19:32:08 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 160227A (trigger=676423).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 194.788, +78.639 which is \n   RA(J2000) = 12h 59m 09s\n   Dec(J2000) = +78d 38' 21\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a early complex\nstructure followed by a stronger peak at around 100 s after the trigger,\nfor a total duration of at least 160 s.  The peak count rate\nwas ~700 counts/sec (15-350 keV), at ~100 sec after the trigger. \n\nThe XRT began observing the field at 19:34:39.9 UT, 151.8 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 194.7974, 78.6768 which is equivalent to:\n   RA(J2000)  = +12h 59m 11.38s\n   Dec(J2000) = +78d 40' 36.5\"\nwith an uncertainty of 5.0 arcseconds (radius, 90% containment). This\nlocation is 136 arcseconds from the BAT onboard position, within the\nBAT error circle. No event data are yet available to determine the\ncolumn density using X-ray spectroscopy. \n\nThe initial flux in the 2.5 s image was 2.67e-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 161 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t12:59:13.84 = 194.80767\n  DEC(J2000) = +78:40:44.9  =  78.67913\nwith a 90%-confidence error radius of about 0.77 arc sec. This position is 11.1\narc sec. from the center of the XRT error circle. The estimated magnitude is\n19.32 with a 1-sigma error of about  0.15. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.05. \n\nBurst Advocate for this burst is M. H. Siegel (siegel 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": 19098,
  "createdOn": 1456602387000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 160227A: Swift detection of a burst with an optical counterpart",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 160227A"
}