GCN Circular 5691

H. Ziaeepour (UCL-MSSL), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), S. R. Oates (UCL-MSSL), C. Pagani (PSU),
K. L. Page (U Leicester), D. M. Palmer (LANL), G. Sato (GSFC/ISAS),
M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester) and
D. E. Vanden Berk (PSU) report on behalf of the Swift Team:

At 19:50:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061004 (trigger=232339).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA,Dec 97.748, -45.894 {06h 30m 60s, -45d 53' 36"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a peak
with a duration of about 6 sec.  The peak count rate
was ~5000 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 19:51:30 UT, 60 seconds after the
BAT trigger. XRT found a bright, variable, uncatalogued X-ray source
located at RA(J2000) = 06h 31m 10.52s, Dec(J2000) = -45d 54' 24.0", with an
estimated uncertainty of 6 arcseconds (90% confidence radius). 
This location is 124 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 2.5s image was
4.6e-10 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 69 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 18.0 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 0.049