GCN Circular 5095

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
M. Capalbi (ASDC), M.L. Conciatore (ASDC), N. Gehrels (NASA/GSFC),
C. Gronwall (PSU), S. T. Holland (GSFC/USRA),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC),
E. Troja (INAF-IASFPA) and L. Vetere (ASDC) report on behalf of the
Swift Team:

At 07:43:27 UT, Swift-BAT triggered and located GRB 060510 (trigger=209351). 
The spacecraft slewed immediately.  The BAT on-board calculated location
is RA,Dec 95.870d,-1.162d {06h 23m 29s,-1d 09' 43"} (J2000), with an
uncertainty of 3 arcmin (radius, 90% containment, stat+sys). 
The BAT light curve shows a multi-peak structure with a total duration
of ~30 sec.  The peak count rate was ~8000 counts/sec (15-350 keV),
at ~1 seconds after the trigger. 

The XRT began observing the field at 07:44:57 UT, 90 seconds after the
BAT trigger. The on-board centroiding algorithm was confused by a cosmic ray 
close to the X-ray afterglow and the position sent out in the automated GCN 
Notice was incorrect.  Using ground-processed data, we find a bright X-ray source
located at RA(J2000) = 06h 23m 28.1s, Dec(J2000) = -01d 09' 44.9", with an
estimated uncertainty of 8 arcseconds (90% confidence radius). 
This location is 11 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 100 seconds after the BAT trigger. 
A fading source was found at RA,Dec = 06h 23m 28.0s -1d 09' 46" (J2000)
with a mag of 18.2.  There is nothing in DSS.  No correction has been made
for the expected extinction corresponding to E(B-V) of 0.41. 

This burst (trigger 209351) should not be confused with the second
Swift-BAT trigger (209352) 38 minutes later.