GCN Circular 7733

S. T. Holland (CRESST/USRA/GSFC), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), E. A. Hoversten (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester) and
E. Troja (U Leicester/INAF-IASFPA) report on behalf of the Swift
Team:

At 00:17:07 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080516 (trigger=311762).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 120.629, -26.176 which is 
   RA(J2000) = 08h 02m 31s
   Dec(J2000) = -26d 10' 33"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 20 sec.  The peak count rate
was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 00:18:29.9 UT, 82.9 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 120.64234, -26.15900
which is equivalent to:
   RA(J2000)  = 08h 02m 34.16s
   Dec(J2000) = -26d 09' 32.4"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This is
75 arcsec from the BAT position, within the BAT error circle. 

UVOT took a finding chart exposure of nominal 400 seconds with the V 
filter  starting 81 seconds after the BAT trigger. No afterglow 
candidate has been  found in the initial data products. This is a 
particularly crowded field with many stars.  The 8'x8' region for 
the list of sources  generated on-board covers  100% of the XRT 
error circle. The limiting  magnitude is about  17.7. No correction has
been made  for the large, but uncertain extinction  expected. 

Burst Advocate for this burst is S. T. Holland (sholland AT milkyway.gsfc.nasa.gov). 
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.)