GCN Circular 30905

E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA),
V. D'Elia (SSDC & INAF-OAR), J.D. Gropp (PSU), S. Laha (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 00:43:19 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a marginal peak (trigger=1076121).  Swift slewed immediately
to the location.  The BAT on-board calculated location is 
RA, Dec 71.470, +12.040 which is 
   RA(J2000) = 04h 45m 53s
   Dec(J2000) = +12d 02' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve does not show
any significant activity. 

The XRT began observing the field at 00:44:28.8 UT, 69.2 seconds after
the BAT trigger. No source was detected in 461 s of promptly downlinked
data. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
284 seconds after the BAT trigger. No credible afterglow candidate has been
found in the initial data products. The 2.7'x2.7' sub-image covers 24% of the
BAT error circle. The typical 3-sigma upper limit has been about 19.2 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 18.0 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.411. 

Due to the marginal significance of the image peak (6.54 sigma), the
lack of a peak in the light curve, the existence of a noisy pixel in
the BAT detector plane histogram, and the lack of a detection
of a counterpart by XRT, we believe that this trigger is
not due to an astrophysical event.