{
  "bibcode": "2017GCN.20538....1M",
  "body": "C. B. Markwardt (NASA/GSFC), S. D. Barthelmy (GSFC),\nS. B. Cenko (GSFC), A. Cholden-Brown (PSU), A. D'Ai (INAF-IASFPA),\nV. D'Elia (ASDC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),\nD. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the\nSwift Team:\n\nAt 14:21:15 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 170127A (trigger=735326).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 174.336, -45.852, which is \n   RA(J2000)  =  11h 37m 21s\n   Dec(J2000) = -45d 51' 05\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a couple weak peaks\nwith a duration of about 35 sec.  The peak count rate\nwas ~900 counts/sec (15-350 keV), at ~5 sec after the trigger. \n\nThe XRT began observing the field at 14:22:51.5 UT, 95.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 174.35974, -45.83603 which\nis equivalent to:\n   RA(J2000)  = 11h 37m 26.34s\n   Dec(J2000) = -45d 50' 09.7\"\nwith an uncertainty of 4.1 arcseconds (radius, 90% containment). This\nlocation is 82 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 7.10e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 250 seconds with the U filter starting\n101 seconds after the BAT trigger. No credible afterglow candidate has been\nfound in the initial data products. The 2.7'x2.7' sub-image covers 100% of the\nXRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The\n8'x8' region for the list of sources generated on-board covers 100% of the XRT\nerror circle. The list of sources is typically complete to about 18.0 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.07. \n\nBurst Advocate for this burst is C. B. Markwardt (Craig.Markwardt 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": 20538,
  "createdOn": 1485527589000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 170127A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 170127A"
}