{
  "bibcode": "2017GCN.21409....1L",
  "body": "S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester),\nD. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf\nof the Swift Team:\n\nAt 05:08:36 UT, the Swift Burst Alert Telescope (BAT) detected a marginal\npeak in the image domain (trigger=766161). Swift slewed immediately to the\nlocation. The BAT on-board calculated location is \nRA, Dec 230.833, -19.547 which is \n   RA(J2000) = 15h 23m 20s\n   Dec(J2000) = -19d 32' 49\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is usual with an image trigger, the available\nBAT light curve shows no significant structure. \n\nThe XRT began observing the field at 05:11:04.0 UT, 147.5 seconds after\nthe BAT trigger. No source was detected in 1.4 ks of promptly\ndownlinked data, which covered 98% of the BAT error circle. We are\nwaiting for the full dataset to detect and localise the XRT\ncounterpart. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 150 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\n0.14. \n\nGround re-analysis of the detector histogram shows a greatly reduced\nsignificance (from 7.3 to 4.2 sigma).  This, combined with the lack\nof a rate trigger and the non-detection of a counterpart by XRT,\nleads us to conclude that this is probably a statistical fluctuation \nin the image plane and not an astrophysical source.",
  "circularId": 21409,
  "createdOn": 1501825210000,
  "email": "palmer@lanl.gov",
  "subject": "Swift Trigger 766161 is not a GRB",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}