TITLE: GCN CIRCULAR NUMBER: 32941 SUBJECT: GRB 221115B: Swift/BAT-GUANO arcminute localization DATE: 22/11/15 23:40:37 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 221115B onboard (T0: 2022-11-15T09:46:15 UTC, CALET trig 1352540756). The CALET 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 in a 2.048 s analysis time bin with a sqrt(TS) of 27.7. The duration of the burst as seen by BAT is ~5 seconds. A confident arcminute localization is found with DeltaLLHPeak of 49. See Section 9.1 and Figure 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. The BAT position is RA, Dec = 54.788, -16.701 deg which is RA(J2000) = 03h 39m 09.16s Dec(J2000) = -16d 42′ 03.5″ with an estimated uncertainty of 3 arcmin. XRT and UVOT follow-up has been requested, but will be significantly delayed due to operational constraints. We encourage followup from other facilities. 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/