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GCN Circular 31572

GRB 220210A: Swift/BAT-GUANO localization
2022-02-11T04:27:48Z (2 years ago)
Aaron Tohuvavohu at U Toronto <>
Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri
Raman (PSU), Jamie A. Kennea (PSU), report:

Swift/BAT did not localize GRB 220210A onboard (T0: 2022-02-10T23:56:38
 UTC, Fermi/GBM GCN 31568, CALET trig 1328572556).

The Fermi and CALET notices, 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, 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 GRB is clearly detected in the BAT data, with a duration of ~15 seconds.
A location for the burst is found with conventional BAT imaging, with SNR 11.4.

While the derived location is precise to ~2 arcminute with respect to
the spacecraft pointing, the conversion to celestial coordinates is
complicated by the current operational mode of Swift (GCN 31500,

The BAT position is
RA, Dec = 345.778, +61.826 deg which is
   RA(J2000)  = 23h 03m 6.9s
   Dec(J2000) = +61d 49��� 33.2���
with an estimated uncertainty of 2 arcmin with respect to the
spacecraft pointing.
The uncertainty in the Swift attitude in the current mode is believed
to be ~1-2 degrees (M. Ajello et al, 2008 ApJ 689, 666).

The position is consistent with the Fermi/GBM localization (GCN 31568).

NITRATES results are not yet available, and will be reported in a
future circular.

There will be no XRT/UVOT followup (GCN 31547).
We encourage followup from other instruments.

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.
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