{
  "bibcode": "2018GCN.22928....1B",
  "body": "S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC),\nS. W. K Emery (UCL-MSSL), J.D. Gropp (PSU), N. P. M. Kuin (UCL-MSSL),\nS. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC) and A. Tohuvavohu (PSU)\nreport on behalf of the Neil Gehrels Swift Observatory Team:\n\nAt 13:33:38 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated a low significance source (trigger=846740).  Swift slewed immediately\nto the location.  The BAT on-board calculated location is \nRA, Dec 198.919, +41.897, which is \n   RA(J2000)  =  13h 15m 41s\n   Dec(J2000) = +41d 53' 50\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for image triggers, the real time\nlight curve does not show anything significant.  Further, this trigger is\nvery weak with a 5.93 sigma in the image domain.  This low-significance trigger\nwas due to being near NGC5055. \n\nThe XRT began observing the field at 13:36:28.0 UT, 169.3 seconds after\nthe BAT trigger. No source was detected in promptly downlinked\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 173 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\nGiven the low significance in BAT and the lack of a detection in XRT, we believe\nthis to be a noise fluctuation trigger near a known galaxy (NGC5055).  Further\nanalysis will be done when the full data set is downloaded.",
  "circularId": 22928,
  "createdOn": 1531058121000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "Trigger 846740: Swift trigger near NGC5055",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>"
}