TITLE: GCN CIRCULAR NUMBER: 33027 SUBJECT: GRB 221206B: Swift/BAT-GUANO candidate arcminute localization DATE: 22/12/06 21:12:13 GMT FROM: Aaron Tohuvavohu at U Toronto James DeLaunay (U Alabama), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Gayathri Raman (PSU), report: Swift/BAT did not trigger on GRB 221206 (T0: 2022-12-06T12:22:47 UTC, Fermi/GBM GCN 33023). The Fermi/GBM 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). Upon 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. The burst is detected in BAT with a duration of ~12 seconds. The burst occurred during a Swift slew. A candidate location for the burst was found with an SNR of 6.6. The BAT position is RA, Dec = 251.155, +42.671 deg which is RA(J2000) = 16h 44m 37.13s Dec(J2000) = +42d 40′ 17.0″ with an estimated uncertainty of 4 arcmin. This position is consistent with the Ferm/GBM localization (GCN 33023). XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/