GCN Circular 6305

A. M. Parsons (GSFC), D. N. Burrows (PSU), M. Capalbi (ASDC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
C. Guidorzi (Univ Bicocca&INAF-OAB), W. B. Landsman (NASA/GSFC),
C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC),
P. T. O'Brien (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC),
P. Romano (Univ. Bicocca & INAF-OAB), E. Troja (INAF-IASFPA) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:

At 10:44:05 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070419B (trigger=276212).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 315.719, -31.267 which is 
   RA(J2000) = 21h 02m 52s
   Dec(J2000) = -31d 15' 59"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows multiple peaks,
with a duration of about 160 seconds. The peak count rate was 
~2500 counts/sec (15-350 keV), at ~0 sec after the trigger.  
We note that this burst is distinct from GRB 070419A (trigger 276206). 

The XRT began observing the field at 10:45:26 UT, 81 seconds after the
BAT trigger. XRT found a bright, fading and uncatalogued X-ray source
located at RA, Dec 315.7067, -31.2635 which is
   RA(J2000)  =  21h 02m 49.6s
   Dec(J2000) = -31d 15' 48.6"
with an uncertainty of 5 arcseconds (radius, 90% containment). 
This location is 40 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 2.5s image
was 1.5e-08 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 89 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. 
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 extinction.