GCN Circular 5055

E. Troja (INAF-IASFPA), S. D. Barthelmy (GSFC),
P. T. Boyd (NASA/GSFC), D. N. Burrows (PSU),
J. R. Cummings (NASA/ORAU), N. Gehrels (NASA/GSFC),
S. T. Holland (GSFC/USRA), S. D. Hunsberger (PSU),
J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA),
V. La Parola (INAF-IASFPA), V. Mangano (INAF-IASFPA),
F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (NASA/ORAU), G. Tagliaferri (INAF-OAB) and
D. E. Vanden Berk (PSU) report on behalf of the Swift Team:

At 17:24:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located the short GRB 060502B (trigger=208275).  Swift slewed immediately
to the burst.  The BAT on-board calculated location is 
RA,Dec 278.936, +52.632 {18h 35m 45s, +52d 37' 56"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The TDRSS BAT light curve shows a single spike
with a FWHM of less than 128 msec.  The peak count rate
was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began taking data at 17:25:51 UT, 70 seconds after the BAT
trigger. The XRT on-board centroid algorithm did not find a source in
the image, however analysis of downlinked data reveals a faint point
source at the following coordinates: RA(J2000) = 18h 35m 45.9s,
Dec(J2000) = 52d 37m 38.1s, with an estimated uncertainty of 10
arcseconds radius (90% containment). This position is 20 arcseconds
from BAT localization. We note that the XRT position lies 2.5
arcseconds from an possible galaxy with R=18.5 in the APM-North
catalogue (McMahon et al., 2000). 

UVOT took a finding chart exposure of 100 seconds with the White 
(160-650 nm) filter starting 74.2 seconds after the BAT trigger. 
There is no detected new source in the rapidly available 2.7'x2.7' 
sub-image, to a limiting White magnitude of about 19.1. 

We are currently in the beginning of the Malindi downlink gap, so we
will not have the full data set until at least 01:00 03/May/06 UT.