[vsnet-grb-info 6912] Swift-BAT Trigger 334129: possible burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8502
SUBJECT: Swift-BAT Trigger 334129: possible burst
DATE:    08/11/09 14:11:03 GMT
FROM:    David Palmer at LANL  <palmer at lanl.gov>

S. Immler (CRESST/GSFC/UMD), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
C. Guidorzi (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC),
S. D. Hunsberger (PSU), N. P. M. Kuin (MSSL), J. Mao (INAF-OAB),
F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-IASFPA), R. L. C. Starling (U Leicester),
G. Tagliaferri (INAF-OAB) and L. Vetere (PSU) report on behalf of the
Swift Team:

At 13:47:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a possible source (trigger=334129).  Swift slewed immediately to 
the location.  The BAT on-board calculated location is 
RA, Dec 350.157, -55.904 which is 
   RA(J2000) = 23h 20m 38s
   Dec(J2000) = -55d 54' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  This was a 128-second image trigger. 
As is usual for image triggers, the BAT light curve showed 
no significant peaks. 

The XRT began observing the field at 13:50:19.9 UT, 183.1 seconds after
the BAT trigger. No source was detected in the promptly available XRT
data. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 187 seconds after the BAT trigger.  We do not detect
an optical afterglow in any of the UVOT data.  The 2.7'x2.7' sub-image
covers 25%  of the BAT error circle with a typical 3-sigma upper limit
has been about 19.6  mag.  The 8'x8' region for the list of sources
generated on-board covers 100% of  the BAT error circle.  The list of
sources is typically complete to about 18  mag.  No correction has
been made for the expected extinction corresponding to  E(B-V) of
0.01. 

Due to the marginal significance of the BAT image and
the non-detection of any source by XRT and UVOT, we
cannot confirm that this is a real source.  Further
analysis will require the Malindi data, which will 
be downlinked at T+8 hours. 

Burst Advocate for this trigger is S. Immler (immler at milkyway.gsfc.nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this trigger. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)