{
  "bibcode": "2018GCN.22449....1B",
  "body": "S. D. Barthelmy (GSFC), J.D. Gropp (PSU), J. A. Kennea (PSU),\nH. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),\nK. L. Page (U Leicester), D. M. Palmer (LANL) and A. Tohuvavohu (PSU)\nreport on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 20:30:51 UT, the Swift Burst Alert Telescope (BAT) triggered on a noise peak\n(trigger=811686).  Swift slewed immediately. \nThe BAT on-board calculated location is \nRA, Dec 185.609, +29.293, which is \n   RA(J2000)  =  12h 22m 26s\n   Dec(J2000) = +29d 17' 34\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for an image trigger, there is nothing\nsignificant in the real-time light curve. \n\nThe XRT began observing the field at 20:33:42.7 UT, 171.3 seconds after\nthe BAT trigger. No source was detected in 406 s of promptly downlinked\ndata. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 178 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\n0.02. \n\nSwift followed up on this location due to a program of verifying\nmarginal detections that happen to be near the locations of\nnearby galaxies.  However, due to the low significance (6.2 sigma)\nof the image peak, the lack of a corresponding count rate increase,\nand the non-detection of an XRT counterpart, we believe that this\nis probably a statistical fluctuation and not an astrophysical source. \n\nFurther determination of the reality of this event will require the \nfull downlinked data.",
  "circularId": 22449,
  "createdOn": 1519591491000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "Swift Trigger 811686 is probably not an astrophysical source.",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>"
}