[vsnet-grb-info 20860] Swift Trigger 848621 is not an astrophysical event

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22958
SUBJECT: Swift Trigger 848621 is not an astrophysical event
DATE:    18/07/18 22:09:09 GMT
FROM:    David Palmer at LANL  <palmer at lanl.gov>

J.D. Gropp (PSU), J. A. Kennea (PSU), D. M. Palmer (LANL),
B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 21:54:34 UT, the Swift Burst Alert Telescope (BAT) found a 
marginal-significance peak in an untriggered image near the
line of site to a nearby galaxy (trigger=848621).  
Swift did not slew to the location due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 190.395, +11.798 which is 
   RA(J2000) = 12h 41m 35s
   Dec(J2000) = +11d 47' 53"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical for an image trigger,
no variation is apparent in the BAT lightcurve. 

BAT alerted due to a program of following up marginal detections
in the vicinity of nearby galaxies.  In this case, the low significance
of the image peak (5.86 sigma), the lack of a rate trigger, and the 
distance between the peak and the putative host galaxy (9 arcmin),
implies that this is merely a noise peak in image space and
not an astrophysical event. 

No further observations are planned.