TITLE:   GCN CIRCULAR
NUMBER:  37222
SUBJECT: Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
DATE:    24/08/21 20:59:43 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


S. Dichiara (PSU) and D. M. Palmer (LANL) report on behalf of the Neil
Gehrels Swift Observatory Team:

At 20:29:24 on 2024-08-21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located the soft gamma repeater SGR 1E 1841-045 / Kes 73 (trigger=1249878). 
Swift did not slew immediately to this source. 
The BAT on-board calculated location is 
RA, Dec 280.344, -4.950 which is 
   RA(J2000) = 18h 41m 22s
   Dec(J2000) = -04d 57' 00"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single spike
structure with a duration of about 0.2 sec.  The peak count rate
was ~100k counts/sec (15-350 keV), at ~0 sec after the trigger. 

Because Swift did not slew, there is no immediate UVOT or XRT data. 
However a Target Of Opportunity observation is currently scheduled
for 3:50 on 2024-08-22 UT. 

This follows a previously-reported burst from this source 25 hours earlier
(GCN #37211) and two additional bursts detected since then, indicating that
this source has entered a bursting phase.  This is the first BAT-detected
activity from this source since 2016.  The current BAT catalog of burst
times for this source is:

2010-05-06T14:37:44
2011-02-08T19:17:27
2011-02-18T07:11:40
2011-02-18T08:57:46
2011-03-06T08:19:49
2011-06-23T14:41:42
2011-07-02T08:38:38
2012-07-15T04:31:08
2012-12-23T22:44:35
2013-09-03T04:28:31
2015-07-15T18:12:38
2016-10-07T18:52:00
2016-10-07T18:55:37
2024-08-20T19:01:18
2024-08-21T07:33:27
2024-08-21T12:16:10
2024-08-21T20:29:24 (this event)