{
  "bibcode": "2010GCN.11315....1C",
  "body": "J. R. Cummings (NASA/UMBC), D. N. Burrows (PSU),\nO. Godet (U Leicester), C. Guidorzi (U Ferrara),\nS. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),\nW.B Landsman (GSFC), V. Mangano (INAF-IASFPA), R. Margutti (INAF-OAB),\nC. B. Markwardt (NASA/GSFC), A. Melandri (INAF-OAB),\nK. L. Page (U Leicester), B. Sbarufatti (INAF-OAB/IASFPA) and\nC. A. Swenson (PSU) report on behalf of the Swift Team:\n\nAt 09:18:01 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated trigger 435520.  Swift slewed immediately to the location. \nThe BAT on-board calculated location is RA, Dec 300.937, +32.386 which is \n   RA(J2000) = 20h 03m 45s\n   Dec(J2000) = +32d 23' 11\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve does not show any obvious\nsignal, which is typical for image triggers.  Based on ground processing\nof flight detector image data, the significance is 6.2 sigma, which \nwould not normally exceed the detection criteria.  We would need additional\nevent-by-event data processed on the ground to clarify the significance. \n\nThe XRT began observing the field at 09:20:24.85 UT,   143.1 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 147 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. Because of the density of catalogued stars, further\nanalysis is required to report an upper limit for any afterglow in the\nsub-image. The coverage of the BAT error circle by the 8'x8' region for the\nlist of sources generated on-board is uncertain because the large number of\nsources filled the available telemetry. Because of the density of catalogued\nstars, further analysis is required to report an upper limit for any afterglow\nin the region. No correction has been made for the large, but uncertain\nextinction expected.",
  "circularId": 11315,
  "createdOn": 1286098864000,
  "email": "kennea@astro.psu.edu",
  "subject": "Swift Trigger 435520 is probably not a GRB",
  "submitter": "Jamie A. Kennea at PSU/Swift-XRT  <kennea@astro.psu.edu>"
}