  We report here on serendipitous observations of the intense gamma-ray flare
from SGR 1806-20 that occured on 27 December 2004. Unique data from the Cluster
and Double Star-2 satellites, designed to study the Earth's magnetosphere,
provide the first observational evidence of three separate timescales within
the early (first 100ms) phases of this class of events. These observations
reveal that, in addition to the initial very steep (<0.25ms) X-ray onset, there
is firstly a 4.9ms exponential rise timescale followed by a continued
exponential rise in intensity on a timescale of 70ms. These three timescales
are a prominent feature of current theoretical models including the timescale
(several ms) for fracture propagation in the crust of the neutron star.
