GCN Circular 13202
Subject
BAT trigger 519207 was a burst from Cyg X-1, was not GRB 120402A
Date
2012-04-03T20:32:51Z (13 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>
J. R. Cummings (GSFC/UMBC), C. B. Markwardt (GSFC), and
T. Sakamoto (NASA/UMBC) on behalf of the Swift-BAT team
The BAT trigger# 519207 (Barthelmy et al, GCN Circ# 13190) has been
identified as due to a flare from Cyg X-1, not a GRB. The maskweighted
BAT lightcurve for Cyg X-1 shows a single symmetric pulse in the
15-50 keV band, about 4 seconds long at the same time as the BAT
trigger. The BAT triggered on the Cyg X-1 flare. While the on-board
processing ignores known bright sources, a portion of the Cyg X-1 flare
appeared in a spatially separate side-lobe, which the BAT did
trigger on.