[vsnet-grb-info 14688] Swift Trigger 592558 is not an astrophysical source

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16002
SUBJECT: Swift Trigger 592558 is not an astrophysical source
DATE:    14/03/20 06:43:54 GMT
FROM:    David Palmer at LANL  <palmer at lanl.gov>

C. J. Mountford (U Leicester), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 06:11:00 UT, the Swift Burst Alert Telescope (BAT) found a 
marginal-significance peak (5.83 sigma) in a non-rate-triggered 
64 second image (trigger=592558).  Because the peak location was close
(8.5 arcminutes) to a nearby galaxy, Swift slewed immediately to the 
location to make a confirmation observation with the narrow-field instruments. 
The BAT on-board calculated location is 
RA, Dec 190.636, +11.579 which is 
   RA(J2000) = 12h 42m 33s
   Dec(J2000) = +11d 34' 44"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows no obvious count
rate variation. 

The XRT began observing the field at 06:13:02.6 UT, 122.5 seconds after
the BAT trigger. No source was detected in 1.2 ks of promptly
downlinked data, which covered 97% of the BAT error circle. 

Given the sub-threshold nature of the trigger, the lack of features in
the BAT light-curve and the fact that no X-ray source is detected, we
believe this was just a noise event.