[vsnet-grb-info 17269] Swift Trigger 664610 is not astrophysical

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18633
SUBJECT: Swift Trigger 664610 is not astrophysical
DATE:    15/11/22 18:23:10 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. Barthelmy (GSFC), K. L. Page (U Leicester), and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift Team:

Analyzing the full downlinked BAT data for Swift trigger 664610 (GCN Circ 18631)
shows the image significance has dropped to 3.2 sigma, well below the 6.5 sigma
requirement.

In 4.9 ks of XRT data, starting 9.3 ks after the trigger, no X-ray sources
are detected within the BAT error circle, to a 3-sigma upper limit of
2.3e-3 count s^-1.  For a typical GRB spectrum, this corresponds to a
0.3-10 keV observed flux limit of 9e-14 erg cm^-2 s^-1.

The combined data from BAT and XRT now show this trigger to be due to noise,
and is not astrophysical.