TITLE:   GCN CIRCULAR
NUMBER:  33960
SUBJECT: GRB 230614B: Swift/BAT-GUANO detection outside the coded FOV 
DATE:    23/06/14 16:17:40 GMT
FROM:    Jimmy DeLaunay at University of Alabama  <delauj2@gmail.com>

James DeLaunay (U Alabama), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Aaron Tohuvavohu (U Toronto) report: 

Swift/BAT did not localize GRB 230614B onboard (T0: 2023-06-14T09:15:01 UTC, Fermi/GBM trig 708426906, GCN 33958) 

The Fermi 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 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 16.18 in a 4.096 s analysis time bin. 
NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of 1.
The Fermi/GBM localization is consistent with being outside the BAT FOV (GCN 33958). 

See Section 9.1 and Figures 10 and 17 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/