{
  "bibcode": "2007GCN..6299....1G",
  "body": "C. Guidorzi (Univ Bicocca&INAF-OAB), A. P. Beardmore (U Leicester),\nD. N. Burrows (PSU), N. Gehrels (NASA/GSFC),\nS. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU),\nH. A. Krimm (GSFC/USRA), W. B. Landsman (NASA/GSFC),\nV. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD),\nF. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),\nJ. P. Osborne (U Leicester), K. L. Page (U Leicester),\nD. M. Palmer (LANL), A. M. Parsons (GSFC), M. Perri (ASDC),\nP. Romano (Univ. Bicocca & INAF-OAB), B. Sbarufatti (INAF-IASFPA),\nP. Schady (MSSL-UCL), M. Stamatikos (NASA/ORAU),\nG. Tagliaferri (INAF-OAB), E. Troja (INAF-IASFPA),\nD. E. Vanden Berk (PSU) and H. Ziaeepour (UCL-MSSL) report on behalf\nof the Swift Team:\n\nAt 11:21:01 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated a marginal-significance image peak that may be GRB 070418\n(trigger=276045).  Swift slewed immediately to the location. \nThe BAT on-board calculated location is \nRA, Dec 228.504, +51.226 which is \n   RA(J2000) = 15h 14m 01s\n   Dec(J2000) = +51d 13' 34\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single\n0.064 second timebin with an excess of ~100 counts above background,\nprimarily in the 100-350 keV energy bin.  The very short duration \nand confinement to the highest energy channel indicate that this\nis very likely to be a cosmic ray shower, although a short, weak,\nvery hard GRB cannot be eliminated at this time.  A final \ndetermination of the cause of this event will \nrequire data from the next Malindi pass, which will be available\naround 1300 UT. \n\nThe XRT began taking data at 11:22:22 UT, 81 seconds after the BAT\ntrigger.  The XRT on-board centroid algorithm did not find a source in the\nimage and no prompt position is available.  Down-linked\ndata (for a total exposure of 1140s) show no sources in the XRT field. \n\nUVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)\nfilter starting 85 seconds after the BAT trigger. No afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 25% of\nthe BAT error circle. The typical 3-sigma upper limit has been about 18.5 mag. \nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nBAT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for extinction of E(B-V)=0.02.",
  "circularId": 6299,
  "createdOn": 1176897045000,
  "email": "palmer@lanl.gov",
  "subject": "Trigger 276045: Swift detection of a possible burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}