{
  "bibcode": "2024GCN.36931....1P",
  "body": "\nK. L. Page (U Leicester), D. M. Palmer (LANL),\nB. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf of\nthe Neil Gehrels Swift Observatory Team:\n\nAt 02:37:36 UT, the Swift Burst Alert Telescope (BAT) triggered on\na rate fluctuation at the 0.032 s timescale and found a low-significance\npeak in the resulting image (trigger=1244778). \nSwift slewed immediately to the location. \nThe BAT on-board calculated location is \nRA, Dec 299.054, -64.667 which is \n   RA(J2000) = 19h 56m 13s\n   Dec(J2000) = -64d 40' 00\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve does not show any\nobvious peak above the noise level. \n\nThe XRT began observing the field at 02:39:04.6 UT, 87.7 seconds after\nthe BAT trigger. No source was detected in 674 s of promptly downlinked\ndata. \n\nUVOT took a finding chart exposure of 250 seconds with the U filter starting\n303 seconds after the BAT trigger. No credible afterglow candidate has been\nfound in the initial data products. The 2.7'x2.7' sub-image covers 25% of the\nBAT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The\n8'x8' region for the list of sources generated on-board covers 100% of the BAT\nerror circle. The list of sources is typically complete to about 18.0 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.068. \n\nDue to the marginal signal in the BAT (6.7 sigma in rates, 6.7 sigma\nin the image) and the lack of an XRT or UVOT counterpart, we believe\nthat this is merely a statistical fluctuation in the BAT image\nreconstruction and not an astrophysical event.  This conclusion\nis expected to be confirmed when the full dataset is available\non the ground. \n\n",
  "subject": "Swift Trigger 1244778 is not a GRB",
  "submitter": "David Palmer at LANL <palmer@lanl.gov>",
  "circularId": 36931,
  "createdOn": 1721876189316,
  "submittedHow": "email"
}