TITLE:   GCN CIRCULAR
NUMBER:  45753
SUBJECT: Swift Trigger 1513439 is probably not a GRB
DATE:    26/09/26 02:43:52 GMT
FROM:    Jimmy DeLaunay at PSU <jjd330@psu.edu>

V. D'Elia (SSDC & INAF-OAR), R. Gupta (NASA GSFC),
A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 02:16:42 UT, the Swift Burst Alert Telescope (BAT) triggered on a rate
increase and located an apparent peak in the image (trigger=1513439).
Swift slewed immediately to the location.
The BAT on-board calculated location is 
RA, Dec = 358.064, +58.474 deg,  which is 
   RA(J2000) = +23h 52m 15s
   Dec(J2000) = +58d 28' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve does not show any
significant GRB-like behavior over the high and smoothly-varying
background count rates, consistent with Swift's location near the SAA.

The XRT began observing the field at 02:20:29.3 UT, 227.5 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image.

Due to the low significance of the image peak (6.5 sigma), the geographical
location of Swift near the fringes of the SAA at the time of the trigger,
leading to the rate increase, and the lack of an XRT counterpart, we believe
that this is probably not due to an astrophysical source.