TITLE: GCN CIRCULAR NUMBER: 31047 SUBJECT: GRB 211105A: Swift/BAT-GUANO detection outside the coded FOV DATE: 21/11/06 02:15:09 GMT FROM: Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com> James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), Jamie A. Kennea (PSU), report: Swift/BAT did not trigger on GRB 211105A (T0: 2021-11-05T04:35:20.2 UTC, GECAM-B GCN #31046). The GECAM 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 BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu, arXiv:2111.01769), detects the burst with a sqrt(TS) of 16 in a 16.384 s analysis time bin. This is the maximum test duration of the search pipeline. The full burst duration in the detector is greater than 60 s. NITRATES prefers an origin for this burst coming from outside the coded FOV, with DeltaLLHOut of -4. An out of FOV origin is consistent with the GECAM localization. See Section 9.1 and Figure 20 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. 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/