{
  "bibcode": "2011GCN.11572....1M",
  "body": "C. B. Markwardt (NASA/GSFC), A. P. Beardmore (U Leicester),\nD. N. Burrows (PSU), J. M. Gelbord (PSU),\nS. T. Holland (CRESST/USRA/GSFC), H. A. Krimm (CRESST/GSFC/USRA),\nN. P. M. Kuin (UCL-MSSL), O. M. Littlejohns (U Leicester),\nK. L. Page (U Leicester), D. M. Palmer (LANL),\nP. Romano (INAF-IASFPA), A. Rowlinson (U Leicester),\nB. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU) and\nR. L. C. Starling (U Leicester) report on behalf of the Swift Team:\n\nAt 12:04:25 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated trigger 442539.  Swift slewed immediately to the location. \nThe BAT on-board calculated location is \nRA, Dec 204.936, +55.160 which is \n   RA(J2000) = 13h 39m 45s\n   Dec(J2000) = +55d 09' 37\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is usual with an image trigger, we do not\nsee obvious structure in the BAT light curve with the currently \navailable data.  With ground processing, the image significance is only \n6.7 sigma, which is below our normal image significance threshold. \n\nThe XRT began observing the field at 12:06:53.9 UT, 148.5 seconds after\nthe BAT trigger. No source was detected in the promptly available XRT\ndata. We are waiting for the full dataset to search for an X-ray counterpart. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 154 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 25% of\nthe BAT 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\nBAT 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\n0.01. \n\nDue to the marginal BAT detection of the event (7.4 sigma in the\non-board image, 6.7 sigma in ground-based analysis) and the lack\nof detection by XRT and UVOT, we believe that this is probably not\na true astrophysical event.  Further determination of its reality\nwill require the full downlinked data, available in a few hours. \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": 11572,
  "createdOn": 1295180762000,
  "email": "palmer@lanl.gov",
  "subject": "Swift Trigger 442539 is probably not a GRB",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}