TITLE: GCN CIRCULAR NUMBER: 32891 SUBJECT: GRB 221029A: Swift/BAT-GUANO detection outside the coded FOV DATE: 22/10/29 22:42:43 GMT FROM: Aaron Tohuvavohu at U Toronto James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (GSFC/UMBC) report: Swift/BAT did not localize GRB 221029A onboard (T0: 2022-10-29T01:05:27 UTC, GECAM trig 49, Fermi/GBM trig 688698332, GRBAlpha GCN 32890). 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 51.6 in a 2.048 s analysis time bin. NITRATES results indicate a burst coming from outside the FOV, with DeltaLLHOut of -60. The NITRATES best fit sky location is consistent with the Fermi/GBM 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/