{
  "bibcode": "2011GCN.11857....1U",
  "body": "T. N. Ukwatta (MSU), S. D. Barthelmy (GSFC),\nA. P. Beardmore (U Leicester), N. Gehrels (NASA/GSFC),\nJ. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC),\nJ. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),\nC. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),\nA. Melandri (INAF-OAB), C. Pagani (U Leicester),\nK. L. Page (U Leicester), D. M. Palmer (LANL),\nC. J. Saxton (UCL-MSSL), M. C. Stroh (PSU), C. A. Swenson (PSU) and\nE. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:\n\nAt 00:12:57 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 110402A (trigger=450545).  Swift slewed to the burst at T+9 min. \nThe BAT on-board calculated location is RA, Dec 197.419, +61.242 which is \n   RA(J2000) = 13h 09m 41s\n   Dec(J2000) = +61d 14' 30\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed multiple short spikes\nwith a total duration of about 40 sec.  The peak count rate\nwas ~9000 counts/sec (15-350 keV), at ~5 sec after the trigger. \n\nThe XRT began observing the field at 00:22:01.5 UT, 544.3 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source with an enhanced position: RA, Dec 197.4014,\n61.2527 which is equivalent to:\n   RA(J2000)  = 13h 09m 36.33s\n   Dec(J2000) = +61d 15' 09.6\"\nwith an uncertainty of 2.3 arcseconds (radius, 90% containment). This\nlocation is 49 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 consistent with the Galactic value of 1.62\nx 10^20 cm^-2 (Kalberla et al. 2005). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 547 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 T. N. Ukwatta (tilan.ukwatta AT gmail.com). \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": 11857,
  "createdOn": 1301705281000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 110402A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 110402A"
}