{
  "bibcode": "2012GCN.13182....1B",
  "body": "A. P. Beardmore (U Leicester), W. H. Baumgartner (GSFC/UMBC),\nV. D'Elia (ASDC), A. Maselli (INAF-IASFPA),\nC. J. Mountford (U Leicester), C. Pagani (U Leicester),\nK. L. Page (U Leicester), D. M. Palmer (LANL),\nT. Sakamoto (NASA/UMBC), M. H. Siegel (PSU),\nR. L. C. Starling (U Leicester) and B.-B. Zhang (PSU) report on behalf\nof the Swift Team:\n\nAt 05:24:15 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 120401A (trigger=519043).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 58.068, -17.671 which is \n   RA(J2000) = 03h 52m 16s\n   Dec(J2000) = -17d 40' 15\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for an image trigger, no\nactivity is apparent in the immediately available light curve. \n\nThe XRT began observing the field at 05:26:14.1 UT, 118.3 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 58.0835, -17.6349 which is equivalent to:\n   RA(J2000)  = +03h 52m 20.04s\n   Dec(J2000) = -17d 38' 05.6\"\nwith an uncertainty of 5.4 arcseconds (radius, 90% containment). This\nlocation is 140 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 1.35e-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 127 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\n0.05. \n\nBurst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). \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": 13182,
  "createdOn": 1333258439000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 120401A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 120401A"
}