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GCN Circular 35880

GRB 240305A: Swift/BAT-GUANO arcminute localization of a burst
2024-03-05T21:56:16Z (a month ago)
Jimmy DeLaunay at Penn State <>
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James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC)  report:

Swift/BAT did not localize GRB 240305A onboard (T0: 2024-03-05T09:49:21.26 UTC, Fermi/GBM trigger 731324994).

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.

In ground analysis of the available TTE data, we find the position of
the burst with SNR 9.7 in the image domain using a slew mosaic technique.

The BAT position is
RA, Dec = 6.278, -43.904, which is:
    RA (J2000)     00h 25m 06.72s
    Dec (J2000)  -43d 54' 14.4"
with an estimated uncertainty of 5 arcminutes

XRT and UVOT will not follow-up due to sun constraints.
Results of follow-up observations will be reported in future circulars.

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:
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