{
  "bibcode": "2015GCN.17724....1B",
  "body": "W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (NASA/UMBC),\nH. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC),\nD. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf\nof the Swift Team:\n\nAt 17:00:10 UT, the Swift Burst Alert Telescope (BAT) detected a\nmarginal significance peak in an non-rate-triggered image (trigger=638589).  \nSwift slewed immediately to the location. \nThe BAT on-board calculated location is \nRA, Dec 87.815, -10.422 which is \n   RA(J2000) = 05h 51m 16s\n   Dec(J2000) = -10d 25' 20\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is usual with an image trigger, \nthe available BAT light curve shows no significant structure. \n\nThe XRT began observing the field at 17:09:20.0 UT, 549.5 seconds after\nthe BAT trigger. No source was detected in 416 s of promptly downlinked\ndata, which covered 85% of the BAT error circle. We are waiting for the\nfull dataset to detect and localise the XRT counterpart. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 1267 seconds after the BAT trigger. No credible afterglow candidate\nhas been found in the initial data products. The 2.7'x2.7' sub-image covers 25%\nof the BAT error circle. The typical 3-sigma upper limit has been about 19.6\nmag. The 8'x8' region for the list of sources generated on-board covers 100% of\nthe BAT error circle. The list of sources is typically complete to about 18\nmag. No correction has been made for the expected extinction corresponding to\nE(B-V) of 0.87. \n\nBecause this is a marginal significance detection of a peak\nin a non-rate-triggered image, with no corresponding source\nin the XRT data, we believe that this is noise fluctuation\nand not an astrophysical source.",
  "circularId": 17724,
  "createdOn": 1429551030000,
  "email": "palmer@lanl.gov",
  "subject": "Swift trigger 638589 is probably not an astrophysical source",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}