GCN Circular 6005

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), M. M. Chester (PSU),
G. Cusumano (INAF-IASFPA), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), C. B. Markwardt (GSFC/UMD),
T. Mineo (INAF-IASFPA), K. L. Page (U Leicester),
D. M. Palmer (LANL), P. Romano (Univ. Bicocca & INAF-OAB),
B. Sbarufatti (INAF-IASFPA), M. Stamatikos (NASA/ORAU) and
R. L. C. Starling (U Leicester) report on behalf of the Swift Team:

At 07:22:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070110 (trigger=255445).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 0.910, -52.961 which is 
   RA(J2000)  =  00h 03m 38s
   Dec(J2000) = -52d 57' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a multi-peaked
structure with a duration of about 70 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~18 sec after the trigger. 

The XRT began observing the field at 07:24:15 UT, 93 seconds after the
BAT trigger. XRT found a bright, variable, uncatalogued X-ray source
located at RA(J2000) = 00h 03m 39.6s, Dec(J2000) = -52d 58' 29.1", with an
estimated uncertainty of 4.2 arcseconds (90% confidence radius). 
This is a ground calculated position based on prompt downlinked data. 
This location is 52 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 2.5s image was
2.1e-09 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 104 seconds after the BAT trigger. An
afterglow candidate is apparent at RA=0.9133 (00h 03m 39.20s),
DEC=-52.9740 (-52d 58' 26.3") with an estimated uncertainty of � 1
arcsec, which is 4.6" from the XRT position. The estimated magnitude
is 20.9 (white), with an uncertainty of � 1 mag. Additional data
products are not yet available to confirm the candidate. The
2.7'x2.7' sub-image covers 100% of the XRT error circle. No
correction has been made for the expected extinction corresponding to
E(B-V) of 0.014.