{
  "subject": "Swift detection of Swift J151857.0-572147",
  "submittedHow": "email",
  "body": "\nE. Ambrosi (INAF-IASFPA), V. D'Elia (SSDC & INAF-OAR),\nP. A. Evans (U Leicester), J. A. Kennea (PSU), A. Melandri (INAF-OAR),\nK. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of\nthe Neil Gehrels Swift Observatory Team:\n\nAt 08:53:10 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated Swift J151857.0-572147 (trigger=1218604).  Swift slewed\nimmediately to the object. The BAT on-board calculated location is \nRA, Dec 229.732, -57.354 which is \n   RA(J2000) = 15h 18m 56s\n   Dec(J2000) = -57d 21' 15\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty). As is usual with an image trigger, the\nBAT light curve does not show any significant structure. \n\nThe XRT began observing the field at 08:56:20.6 UT, 189.7 seconds after\nthe BAT trigger. XRT found a bright X-ray source located at RA, Dec\n= 229.7358, -57.3617 which is equivalent to:\n   RA(J2000)  = 15h 18m 56.59s\n   Dec(J2000) = -57d 21' 42.1\"\nwith an uncertainty of 4.7 arcseconds (radius, 90% containment). This\nlocation is 28 arcseconds from the BAT onboard position, within the BAT\nerror circle, and consistent with the localisation of Swift J151857.0-572147\nreported in GCN Circs. 35849 & 35853. \n\nUVOT took a finding chart exposure of 250 seconds with the U filter\nstarting 195 seconds after the BAT trigger. No credible afterglow\ncandidate has been found in the initial data products. \n\nThis object is the same as BAT trigger 1218452, which was originally\nidentified as GRB 240303A (Lien et al., GCN Circ. 35849) but later confirmed\nas a Galactic transient Swift J151857.0-572147 (Kennea et al., GCN Circ. 35853). \n\n",
  "createdOn": 1709543684155,
  "bibcode": "2024GCN.35858....1A",
  "circularId": 35858,
  "submitter": "P.A. Evans at U. Leicester <pae9@leicester.ac.uk>"
}