2. BBSO Halpha fulldisk movies from August 13-25, 1999

• Full disk Halpha movie



• Active region (AR8668) movie

From the movie, we define three periods of the development of the sigmoid filament:

(1) Forming period: Aug15 - 17; typical of small flare events around the filamented filament structure, mostly involving eruptions.

(2) Maturing period: Aug18 - 19; fully developed sigmoid filament, and filament activation - growing thick and rising.

(3) Disintegrating period: > Aug20; filament broken from the saddle point, where small AFSs are formed.

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