TITLE:   GCN CIRCULAR
NUMBER:  17759
SUBJECT: GRB 150424A: spectral lag, extended-time emission
DATE:    15/04/25 01:52:26 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

J. P. Norris (BSU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
and N. Gehrels (GSFC) report:

We report spectral lag and extended emission measurements for the intense,
short GRB 150424A (trigger=638946; GCN Circ. 17743, 17745 & 17756) based
on Swift-BAT data.

Using a 4-ms binned light curve, the lag for the 25-50 keV to 100-350 keV bands
is estimated as 0.6 (+0.6/-1.0) ms; and -2.4 (+1.3/-0.7) ms for the 15-25 keV
to 50-100 keV bands.

A Bayesian Block analysis of the mask-tagged data reveals one significant
block of duration ~ 106 seconds at a level of 0.006 counts/det/s, following
the intense, initial pulse complex.  This extended emission component is
three orders of magnitude lower than the peak intensity of the burst,
~ 5.3 counts/pixel/s.