[vsnet-grb-info 16435] Confirmation that Swift trigger 638217 is not an astrophysical source

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17716
SUBJECT: Confirmation that Swift trigger 638217 is not an astrophysical source
DATE:    15/04/17 14:49:12 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm at nasa.gov>

H. A. Krimm (CRESST/GSFC/USRA) and B. Sbarufatti (INAF-OAB/PSU) report on behalf 
of the Swift Team:

We conclude that Swift trigger #638217 (Gehrels, et al., GCN Circ. 17712) was
the result of noise fluctuations and is not due to a GRB or other astrophysical
event.

We have analyzed the BAT data set from T-239 to T+440 sec from the recent
telemetry downlink.  We find that there is no sign of significant emission from
the trigger location at any point in this interval.

XRT observations in Photon Counting mode data started 152 s after the BAT 
trigger. In 1.9 ks of PC data no source is detected inside the BAT error circle. 
The three sigma upper limit is 9.5e-3 counts/second.