TITLE:   GCN CIRCULAR
NUMBER:  6718
SUBJECT: GRB 070808: Swift detection of a burst
DATE:    07/08/08 18:50:12 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU),
H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL), P. Romano (Univ. Bicocca & INAF-OAB),
G. Sato (GSFC/ISAS), M. Stamatikos (NASA/ORAU),
R. L. C. Starling (U Leicester), E. Troja (INAF-IASFPA),
T. N. Ukwatta (GSFC/GWU) and D. E. Vanden Berk (PSU) report on behalf
of the Swift Team:

At 18:28:00 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070808 (trigger=287260).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 6.766, +1.166 which is 
   RA(J2000)  =  00h 27m 04s
   Dec(J2000) = +01d 09' 59"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single FRED peak
structure with a duration of about 10 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began taking data at 18:29:54 UT, 114 seconds after the BAT
trigger. Using prompt downlinked data, we find a fading, uncatalogued
X-ray source located at RA, Dec: 6.7628, 1.1758 which is
   RA(J2000)  = 00 27 03.08
   Dec(J2000) = +01 10 32.7
with an uncertainty of 4.5 arcsec (radius, 90% containment). 
This location is 36 arcseconds from the BAT on-board position, within 
the BAT error circle. 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 118 seconds after the BAT trigger. No afterglow candidate has
been found in the initial data products. The 2.7' x 2.7' sub-image covers 100%
of the XRT error circle. The typical 3-sigma upper limit has been about 18.5 mag. 
No correction has been made for the expected extinction corresponding
to E(B-V) of 0.02 mag. 

Burst Advocate for this burst is J. R. Cummings (jayc 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.)