GCN Circular 7873

C. B. Markwardt (CRESST/GSFC/UMD), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), G. Cusumano (INAF-IASFPA),
C. Gronwall (PSU), C. Guidorzi (INAF-OAB),
S. T. Holland (CRESST/USRA/GSFC), J. Mao (INAF-OAB),
F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),
J. P. Osborne (U Leicester), K. L. Page (U Leicester),
M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester),
G. Tagliaferri (INAF-OAB) and H. Ziaeepour (UCL-MSSL) report on
behalf of the Swift Team:

At 11:12:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080613B (trigger=313954).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is
RA, Dec 173.797, -7.098 which is
   RA(J2000) = 11h 35m 11s
   Dec(J2000) = -07d 05' 53"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty).  The BAT light curve shows multiple overlapping
peaks with a duration of about 50 sec.  The peak count rate
was ~10000 counts/sec (15-350 keV), at ~T+0 sec after the trigger. 

The XRT began observing the field at 11:13:47.4 UT, 69.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 173.79896, -7.10590 which
is equivalent to:
   RA(J2000)  = 11h 35m 11.75s
   Dec(J2000) = -07d 06' 21.2"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 29 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 3.83e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 79 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 3-sigma upper limit is 19.7 mag. 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 mag. No correction has been
made for the expected extinction corresponding to E(B-V) of 0.04. 

Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT 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.)