[vsnet-grb-info 14079] Swift-BAT Trigger 575905 is probably not a real source

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15393
SUBJECT: Swift-BAT Trigger 575905 is probably not a real source
DATE:    13/10/28 17:34:05 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings at nasa.gov>

J. R. Cummings and Valerio D'Elia on behalf of the Swift science team

Swift-BAT trigger 575905 (Cenko et al., GCN 15384) is probably due to a
fluctuation in the image domain, not to any astrophysical source.  While
the BAT significance level (7.0 sigma) usually is high enough to indicate
a real source, in this case the peak in the image is not robust with
respect to very slight changes in parameters.

The total XRT exposure for this field is 15ks. The source number 2 reported
in Izzo et al. (GCN 15388), that was uncatalogued but below the RASS limit,
has a bright star as optical counterpart. We thus conclude that source 2 is
not related to the BAT emission, and that the slight variability observed
for this object in the X-ray band is due to normal stellar activity.