{
  "bibcode": "2010GCN.10654....1H",
  "body": "E. A. Hoversten (PSU), S. D. Barthelmy (GSFC),\nP. A. Evans (U Leicester), J. M. Gelbord (PSU), D. Grupe (PSU),\nS. T. Holland (CRESST/USRA/GSFC), S. Immler (CRESST/GSFC/UMD),\nW.B Landsman (GSFC), C. B. Markwardt (CRESST/GSFC/UMD),\nD. M. Palmer (LANL), M. H. Siegel (PSU), M. C. Stroh (PSU),\nT. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the\nSwift Team:\n\nAt 02:44:02 UT, the Swift Burst Alert Telescope (BAT) detected\ntrigger 420256.  Swift slewed immediately to the location. \nThe BAT on-board calculated location is \nRA, Dec 271.841, +27.172 which is \n   RA(J2000) = 18h 07m 22s\n   Dec(J2000) = +27d 10' 18\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for an image trigger,\nthere is no obvious variation in the immediately-available lightcurve. \n\nThe XRT began observing the field at 02:46:32.1 UT, 149.9 seconds after\nthe BAT trigger. No source was detected in the promptly available XRT\ndata. We are waiting for the full dataset to detect and localise the\nXRT counterpart. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 153 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\n0.11. \n\nDue to the marginal significance (7.02 sigma) of the initial\ndetection by BAT, and the lack of a source detection by\nXRT, we cannot confirm that this is a true astrophysical source. \nFinal determination of the reality of this detection will require\nanalysis of the Malindi data. \n\nBurst Advocate for this burst is E. A. Hoversten (hoversten AT astro.psu.edu). \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": 10654,
  "createdOn": 1271992191000,
  "email": "palmer@lanl.gov",
  "subject": "Trigger 420256: Swift detection of a possible GRB",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}