[vsnet-grb-info 4211] Trigger 255685: Swift detection of a possible burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6011
SUBJECT: Trigger 255685: Swift detection of a possible burst
DATE:    07/01/11 21:16:20 GMT
FROM:    David Palmer at LANL  <palmer at lanl.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester),
C. Guidorzi (Univ Bicocca&INAF-OAB), S. Immler (GSFC/USRA),
J. A. Kennea (PSU), K. L. Page (U Leicester),
S. B. Pandey (UCL-MSSL), P. Roming (PSU), M. Stamatikos (NASA/ORAU),
R. L. C. Starling (U Leicester) and E. Troja (INAF-IASFPA) report on
behalf of the Swift Team:

At 20:49:45 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a marginal peak which, if a real GRB, would be GRB 070111
(trigger=255685).  The BAT on-board calculated location is 
RA, Dec 99.939, -56.099 which is 
   RA(J2000) = 06h 39m 45s
   Dec(J2000) = -56d 05' 57"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The rate trigger indicates a total of 175 
counts in 32 ms, which is well in excess of background (8 sigma),
but is consistent with the observational characteristics of a 
cosmic ray shower. 

For this reason, it is most likely that this is not a GRB.  However
a final determination will not be possible until we have downlinked
the full data set. 

Because of an Earth limb constraint, the spacecraft did not slew
promptly to the BAT position, and so there are no immediate XRT or
UVOT data products to analyze. Swift NFIs will begin observing this
target at approximately 22:07 UT.