[vsnet-grb-info 16326] Confirmation that Swift trigger 635306 is not an astrophysical source

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17607
SUBJECT: Confirmation that Swift trigger 635306 is not an astrophysical source
DATE:    15/03/18 21:50:04 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm at nasa.gov>

H. A. Krimm (CRESST/GSFC/USRA) and C. Pagani (U Leicester) report on behalf of 
the Swift Team:

We conclude that Swift trigger #635306 (Breeveld, et al., GCN Circ. 17601) 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+963 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 164 s after the BAT 
trigger. In 1ks of PC data no source is detected inside the BAT error circle. 
The three sigma upper limit is 6e-3 counts/second.