{
  "bibcode": "2016GCN.19304....1E",
  "body": "GRB 160409A found in Swift BAT ground analysis\n\nP.A. Evans (U. Leicester),  J.P. Osborne (U Leicester), \nK. L. Page (U Leicester), and  D.M. Palmer (LANL)\nreport on behalf of the Swift Team\n\nAt 05:54:14 UT on 2016-04-09 BAT triggered and located\nGRB 160409A (trigger #682162).  Swift did not immediately \nslew to this source because its location approximately\nmatched a known source (4U 1916-053) in its on-board catalog.  \nThe BAT on-board calculated location is \nRA, dec 289.705,-5.390 which is \nRA(J2000) = 19h 18m 49s\nDec(J2000) = -5d 23' 24\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a complex\npeak structure with a duration of about 30 sec.  The peak count rate\nwas ~1300 counts/sec (15-350 keV), at ~2 sec after the trigger.\n\nThe catalogued source, 4U 1916-053, is identified by Simbad as being\nthe LXB V* V1405 Aql.  However, this object is 9 arcminutes from the \nBAT position, and well outside the error circle.  BAT has detected a burst\nfrom that source (1.1 arcmin offset from the V1405 Aql location)\nin April 2006.  During the 6-minute accumulation that overlaps the\ntrigger, SAX J2103.5+4545 is detected (at lower significance and \ncorrespondingly larger position uncertainty) with a 3.3 arcmin offset.\nTherefore we can confidently state that this trigger did not come\nfrom the location of V1405 Aql and is due to a different source.\n\nA Swift Target of Opportunity was requested and XRT began\nobserving the field at 00:34:58 UT on 2016-04-12, which is\n2.8 days after the BAT trigger. No unknown sources were \ndetected in the 3 kiloseconds of data, although two known \nsources and possible scattered X-rays from V1405 Aql were seen.\nNo new sources were detected in UVOT down to a limiting\nmagnitude of 21.3 in white.\n\nQualitatively, about half of long GRBs would be visible in a \n3 ks XRT observation at that delay after the trigger, so the \nnon-detection of an afterglow does not rule out a GRB.",
  "circularId": 19304,
  "createdOn": 1460488811000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 160409A found in Swift BAT ground analysis",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 160409A"
}