Skip to main content
U.S. flag

An official website of the United States government

GCN Circulars are now part of the new GCN! See news and announcements

GCN Circular 33859

Subject
GRB 230523A: Swift/BAT-GUANO detection of a short hard burst
Date
2023-05-23T22:58:55Z (16 days ago)
From
Aaron Tohuvavohu at University of Toronto <aaron.tohu@gmail.com>
Gayathri Raman (PSU), Samuele Ronchini (PSU), James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 230523A onboard (T0: 2023-05-23T15:23:52.68 UTC, INTEGRAL/SPI-ACS #10268). The INTEGRAL 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 90 seconds of BAT event-mode data from [-45,+45] 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 12.4 in a 1.024 s analysis time bin. The burst duration is ~2 seconds. NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a borderline DeltaLLHOut of 8.33. 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/
Looking for U.S. government information and services? Visit USA.gov