GCN Circular 5096

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),
J. P. Osborne (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. Perri (ASDC) and L. Vetere (ASDC) report on
behalf of the Swift Team:

At 08:22:14 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060510B (trigger=209352).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is RA,Dec 239.141, +78.559
{15h 56m 34s, +78d 33' 33"} (J2000) with an uncertainty of 3 arcmin
(radius, 90% containment, including systematic uncertainty). 
Because this is an image trigger, the TDRSS BAT light curve does not show
any significant activity around the trigger time, but we note that there is
possible activity at T+150 and T+300 sec.  This possible long duration could be 
an indication of a high redshift burst. 

The XRT began observing the field at 08:24:13 UT, 119 seconds after the
BAT trigger. XRT found a bright, possibly fading, uncatalogued X-ray source
located at RA(J2000) = 15h 56m 29.3s, Dec(J2000) = +78d 34' 09.4", with an
estimated uncertainty of 4.7 arcseconds (90% confidence radius). 
This location is 39 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 2.5s image was
7.1e-09 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of nominal 100 seconds with the
White (160-650nm) filter starting 129 seconds after the BAT trigger. 
No afterglow candidate has beeen found in the initial data products. 
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. 

We note that this is the second Swift burst within 38 minutes. Because
the second burst (GRB 060510B) overwrites the first (GRB 060510A) in
the on-board automated observing program, the NFI follow-up
observations for GRB 060510A will not be available until that burst
can be uploaded as a ToO during normal working hours at the Swift
Mission Operations Center.