Additional Bursts from SGR 1935+2154 Seen by Swift BAT

ATel #15141; David Palmer (LANL) on behalf of the Swift Team
on 25 Dec 2021; 03:22 UT
Credential Certification: David M. Palmer (palmer@lanl.gov)

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The recent burst from the soft gamma repeater SGR 1935+2154, seen by AGILE and Fermi GBM at T0=2021-12-24 03:42:34 UT (Ursi et al., GCN #21296) was also detected and localized by Swift BAT, (Trigger #1090704; Burst #1) confirming the identity of the source.

BAT also detected two subsequent weaker bursts at
03:48:01 (Trigger #1090705; T+327s; Burst #2) and
03:51:27 (Trigger #1090706; T+533s; Burst #3).

Burst #1 had a flat-topped profile with a 0.02 s rise, a 0.9 s plateau, and a 0.3 s decay. The count rate during the plateau was 24k counts/s. (All count rates are in the full instrumental band, which extends to slightly lower energies than BAT's usually-reported 15-350 keV band.)

Burst #2 had a simple rise-and-fall peak with a duration of 0.03 s and a peak of 7k counts/s.

Burst #3 had a wider peak with a squarer profile, a duration of 0.10 s and a peak of 2.2k counts/s.

The most recent previous activity of this source seen by BAT was a month-long sequence of 15 bursts, extending from Sept. 11 to Oct. 11 of 2021.