{
  "body": "James DeLaunay (PSU), Aaron Tohuvavohu (Cosmic Frontier), Samuele Ronchini (GSSI), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern)  report:\n\nSwift/BAT did not localize GRB 251103A onboard (T0: 2025-11-03T04:46:28.11 UTC, Fermi Trig 783837993, SVOM Trig sb25110301).\n\nThe Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). \n\nUpon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.\n\nThe BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst in a 2.048 s analysis time bin starting at T0 - 0.0 s with a sqrt(TS) of 61.6.\nAn arcminute localization is found with DeltaLLHOut of 24 and a DeltaLLHPeak of 10.2.\n\nSee Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.\n\nThe BAT position is\nRA, Dec = 146.821, 16.104 deg which is\n   RA(J2000)  = 09h 47m 17.04s\n   Dec(J2000) = 16d 06’ 14.4″\nwith an estimated uncertainty of 5 arcmin radius.\n\nMore details about this burst can be found on the trigger report page here:\n\nhttps://guano.swift.psu.edu/trigger_report?id=783838024\n\nGUANO is a fully autonomous, extremely low latency, spacecraft\ncommanding pipeline designed for targeted recovery of BAT event mode\ndata around the times of compelling astrophysical events to enable\nmore sensitive GRB searches.\n\nA live reporting of Swift/BAT event data recovered by GUANO can be\nfound at: https://www.swift.psu.edu/guano/",
  "eventId": "GRB 251103A",
  "subject": "GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst",
  "circularId": 42568,
  "createdOn": 1762227370923,
  "format": "text/plain",
  "bibcode": "2025GCN.42568....1D",
  "submittedHow": "web",
  "submitter": "Jimmy DeLaunay at Penn State <delauj2@gmail.com>"
}