{
  "subject": "Swift Trigger 1232465 is not a GRB",
  "createdOn": 1717278638247,
  "bibcode": "2024GCN.36593....1G",
  "circularId": 36593,
  "body": "\nJ.D. Gropp (PSU), R. Gupta (NASA/GSFC), A. Y. Lien (U Tampa) and\nD. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 21:30:20 UT, the Swift Burst Alert Telescope (BAT) triggered on\na rate increase and a marginal peak in the resulting image\n(trigger=1232465).  Swift slewed immediately to the peak location. \nThe BAT on-board calculated location is \nRA, Dec 108.731, -6.206 which is \n   RA(J2000) = 07h 14m 55s\n   Dec(J2000) = -06d 12' 20\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty). The available BAT light curve does not show any\nsignificant fluctuations above the noise level. \n\nThe XRT began observing the field at 21:31:59.9 UT, 99.7 seconds after\nthe BAT trigger. No source was detected in 559 s of promptly downlinked\ndata. We are waiting for the full dataset to detect and localise the\nXRT counterpart. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 104 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 large, but uncertain, extinction expected. \n\nDue to the marginal significance of the initial rate trigger (6.5 sigma\nin 0.032 s) and the BAT image (6.8 sigma), and the lack of an observed\ncounterpart in the XRT and UVOT data, we believe that this is probably\na statistical fluctuation and not a real astrophysical event. \n\nFurther analysis of the complete downlinked dataset will be used\nto conclusively rule out this event. \n\n",
  "submittedHow": "email",
  "submitter": "David Palmer at LANL <palmer@lanl.gov>"
}