GCN Circular 7767

M. C. Stroh (PSU), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
C. Gronwall (PSU), D. Grupe (PSU), S. T. Holland (CRESST/USRA/GSFC),
H. A. Krimm (CRESST/GSFC/USRA), V. Mangano (INAF-IASFPA),
P. T. O'Brien (U Leicester), D. M. Palmer (LANL),
D. Perez (U Leicester), J. L. Racusin (PSU),
M. Stamatikos (NASA/ORAU), T. N. Ukwatta (GSFC/GWU) and
D. E. Vanden Berk (PSU) report on behalf of the Swift Team:

At 21:21:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080523 (trigger=312242).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 20.732, -64.053 which is 
   RA(J2000) = 01h 22m 56s
   Dec(J2000) = -64d 03' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 15 sec.  The peak count rate
was ~700 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 21:23:17.7 UT, 86.4 seconds after
the BAT trigger. XRT found a bright, uncatalogued, fading X-ray source located
at RA, Dec 20.7992, -64.0322 which is equivalent to:
   RA(J2000)  = 01h 23m 11.8s
   Dec(J2000) = -64d 01' 55.9"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 129 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to assess possible
redshift constraints using X-ray spectroscopy and the nH-z relation
from Grupe et al. (2007). 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 110 seconds after the BAT trigger. No afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 18.5 mag. 
data for the list of sources generated on-board are not available at this time. 
No correction has been made for the expected extinction corresponding to E(B-V)
of 0.03. 

Burst Advocate for this burst is M. C. Stroh (stroh AT astroh.org). 
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.)