{
  "bibcode": "2016GCN.19595....1D",
  "body": "V. D'Elia (ASDC), C. Gronwall (PSU), L. Izzo (IAA-CSIC),\nF. E. Marshall (NASA/GSFC) and D. M. Palmer (LANL) report on behalf of\nthe Swift Team:\n\nAt 23:30:15 UT, the Swift Burst Alert Telescope (BAT) detected a \nmarginal-significance peak in an image (trigger=701668). \nSwift slewed immediately to the location. \nThe BAT on-board calculated location is \nRA, Dec 186.444, +12.747 which is \n   RA(J2000) = 12h 25m 46s\n   Dec(J2000) = +12d 44' 49\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for image triggers, no\nobvious variation is visible in the immediately-available lightcurve. \n\nThe XRT began observing the field at 23:39:38.0 UT, 562.5 seconds after\nthe BAT trigger. Using promptly downlinked data we find an X-ray source\nwith an enhanced position: RA, Dec 186.4463, 12.6611 which is\nequivalent to:\n   RA(J2000)  = 12h 25m 47.10s\n   Dec(J2000) = +12d 39' 39.9\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nposition may be improved as more data are received; the latest position\nis available at http://www.swift.ac.uk/sper. This position is 6.2\narcseconds from a known X-ray source: 1SXPS J122546.7+123942. This\nsource is in the Swift XRT 1SXPS catalogue with a mean 0.3-10 keV\ncount-rate of 0.1600 +/- 0.0025 ct/sec; see\nhttp://www.swift.ac.uk/1SXPS/1SXPSJ122546.7%2B123942 for details of\nthese previous observations\n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 2.86\nx 10^20 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 567 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 none of\nthe XRT error circle. The 8'x8' region for the list of sources generated\non-board covers none of the XRT error circle. No correction has been made for\nthe expected extinction corresponding to E(B-V) of 0.03. \n\nBecause this location is in the approximate direction of a nearby\ngalaxy (4 arcmin from NGC4387) Swift made follow-up observations\nto confirm or refute the existence of a source, despite the \nmarginal significance (6.34 sigma).  Based on the non-detection\nby XRT and UVOT of any previously uncatalogued source, we believe that\nthis is not an astrophysical event.",
  "circularId": 19595,
  "createdOn": 1466985212000,
  "email": "palmer@lanl.gov",
  "subject": "Swift Trigger 701668 is probably not an astrophysical event",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}