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GCN Circular 12079

Subject
SGR 1E 1841-045: Swift detection of a soft gamma repeater burst
Date
2011-06-23T15:06:07Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
A. Rowlinson (U Leicester), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
S. Campana (INAF-OAB), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC),
J. P. Osborne (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), C. J. Saxton (UCL-MSSL),
B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU),
M. Stamatikos (OSU/NASA/GSFC), C. A. Swenson (PSU) and
G. Tagliaferri (INAF-OAB) report on behalf of the Swift Team:

At 14:41:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located SGR 1E 1841-045 / Kes 73 (trigger=455904).  Swift slewed
immediately to the source.  The BAT on-board calculated location is 
RA, Dec 280.317, -4.937, which is 
   RA(J2000)  =  18h 41m 16s
   Dec(J2000) = -04d 56' 13"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single spike
with a duration of about 0.06 sec.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 14:43:09 UT, 86 seconds
after the BAT trigger. Using promptly downlinked data we find an X-ray
source located at RA, Dec = 280.33047, -4.93562 which is equivalent to:
   RA(J2000)  =  18h 41m 19.3s
   Dec(J2000) = -04d 56m 08.2s
with an uncertainty of 4.6 arcseconds (radius, 90% containment), which is 
2.9 arcseconds from the location of 1E 1841-04.5 (AKA PSR J1841-0456). This
position may be improved as more data are received. 

UVOT took a finding chart exposure of 150 seconds with the white filter starting
89 seconds after the BAT trigger. No credible afterglow candidate has been
found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the
XRT error circle. Because of the density of catalogued stars, further analysis
is required to report an upper limit for any afterglow in the sub-image. The
8'x8' region for the list of sources generated on-board covers 100% of the XRT
error circle. The list of sources is typically complete to about 18.0 mag. No
correction has been made for the large, but uncertain extinction expected. 

Swift has previously triggered on bursts from this source (most recently
on February 8, 2011, GCN 11673, Barthelmy et al.). 

Burst Advocate for this burst is A. Rowlinson (bar7 AT star.le.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
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