[vsnet-grb-info 26158] Swift Trigger 989458 is due to detector noise

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28258
SUBJECT: Swift Trigger 989458 is due to detector noise
DATE:    20/08/17 16:05:35 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

P. D'Avanzo (INAF-OAB) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift team:

Using the full data set from recent downlinks, we report further ground
data analysis for Swift trigger 989458 (Bernardini et al. GCN Circ. 28250).

The BAT analysis uses data from T-61 to T+242 sec. The BAT image
significance has now decreased to 4.8 sigma (15-350 keV). Also, the
mask-weighted light curve does not show anything significant.

Ground analysis of the 0.3 ks of XRT PC mode data confirms that no XRT
counterpart is detected in the BAT error circle.

We thus conclude that this trigger was due to detector noise.