[vsnet-grb-info 16519] Confirmation that Swift Trigger 639636 is not astrophysical

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17800
SUBJECT: Confirmation that Swift Trigger 639636 is not astrophysical
DATE:    15/05/03 01:25:25 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), A. Maselli (INAF-IASFPA), M. Siegel (PSU), P. Kuin (MSSL)
report:

We conclude that Swift trigger #639636 (Maselli, et al., GCN Circ. 17799)
was the result a noise fluctuation in BAT and is not due to a GRB or other
astrophysical event.

We have analyzed the BAT data set from T-239 to T+680 sec from recent
telemetry downlinks.  We find that ground analysis results in the significance
dropping to 4.1 sigma from T+0 to T+60 s.

Using 4.4 ks of XRT data, there is no significant counterpart detected
within the BAT error circle at a three sigma upper limit of 2.84E-03 cts/s.

The UVOT finding chart shows no new source to a limit of 19.6 mag in white.