GCN Circular 15596

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (NASA/UMBC), C. Gronwall (PSU), D. Grupe (PSU),
S. T. Holland (STScI), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
M. H. Siegel (PSU), M. C. Stroh (PSU) and C. A. Swenson (PSU) report
on behalf of the Swift Team:

At 03:26:43 UT, the Swift Burst Alert Telescope (BAT) triggered (581129).  
Swift slewed immediately to the location.  The BAT on-board calculated location
is RA, Dec 178.342, +47.942, which is 
   RA(J2000)  =  11h 53m 22s
   Dec(J2000) = +47d 56' 32"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single very weak peak 
structure with a duration of about 0.1 sec.  The peak count rate
was ~700 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 03:28:03.5 UT, 80.5 seconds after
the BAT trigger. No source was detected in 604 s of promptly downlinked
data, which covered 96% of the BAT error circle. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 83 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 25% of
the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
BAT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.02. 

Due to the low significance in the BAT image and the lack of a detection
in XRT and UVOT, we believe this trigger to be a noise event.