GCN Circular 28258
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.