GCN Circular 14293

B.P. Gompertz (U Leicester), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU), V. D'Elia (ASDC),
S. T. Holland (STScI), C. B. Markwardt (NASA/GSFC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
M. H. Siegel (PSU), R. L. C. Starling (U Leicester),
C. A. Swenson (PSU) and E. Troja (NASA/GSFC/UMCP) report on behalf of
the Swift Team:

At 16:08:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130313A (trigger=550906).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 236.423, -0.362 which is 
   RA(J2000)  =  15h 45m 42s
   Dec(J2000) = -00d 21' 41"
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 0.2 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 16:09:29.2 UT, 78.1 seconds after
the BAT trigger. No source was detected in 737 s of promptly downlinked
data, which covered 93% of the BAT error circle. We are waiting for the
full dataset to detect and localise the XRT counterpart. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 81 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
0.10. 

Burst Advocate for this burst is B.P. Gompertz (bpg6 AT 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.)