{
  "bibcode": "2022GCN.31746....1T",
  "body": "Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri\nRaman (PSU), Jamie A. Kennea (PSU), report:\n\nSwift/BAT did not localize GRB 220310C onboard (T0:\n2022-03-10T22:23:51 UTC, Fermi/GBM GCN 31735).\n\nThe Fermi notice, distributed in near real-time, triggered the Swift\nMission Operations Center operated Gamma-ray Urgent Archiver for Novel\nOpportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).\n\nUpon trigger by this notice, GUANO sent a command to the Swift Burst\nAlert Telescope (BAT) to save 200 seconds of BAT event-mode data from\n[-50,+150] seconds around the time of the burst. All the requested\nevent mode data was delivered to the ground.\n\nThe BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu,\narXiv:2111.01769), detects the burst in a 8.192 s analysis time bin\nwith a sqrt(TS) of 9.7.\nA candidate arcminute localization is found with DeltaLLHOut of 19.7\nand a DeltaLLHPeak of 5.7.\n\nFor this reason we can confidently claim detection, and preference for\nan in FOV origin, but the best fit arcmin localization is not strongly\npreferred over other positions.\nA few burst locations with comparable DeltaLLHPeak have been\npreviously verified with afterglow discovery (eg GRB 211106A).\n\nSee Section 9.1 and Figure 20 in the NITRATES paper for brief\ndescriptions and interpretations of sqrt(TS), DeltaLLHPeak, and\nDeltaLLHOut.\n\nNo source is found with conventional BAT imaging. This is expected\ngiven the strength of the signal in BAT, and its position near the\nedge of the coded FOV.\n\nThe BAT position is\nRA, Dec = 290.069, +40.253 deg which is\n   RA(J2000)  = 19h 20m 16.62s\n   Dec(J2000) = +40d 15��� 12.3���\nwith an estimated uncertainty of 5 arcmin.\n\nThis independent position is consistent with the Fermi/GBM\nlocalization (GCN 31735).\n\nXRT and UVOT follow-up has been requested.\nResults of follow-up observations will be reported in future circulars.\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/",
  "circularId": 31746,
  "createdOn": 1647030638000,
  "email": "aaron.tohu@gmail.com",
  "subject": "GRB 220310C: Swift/BAT-GUANO candidate arcminute localization",
  "submitter": "Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>",
  "eventId": "GRB 220310C"
}