Sigmoid to Cusped Arcade

The images show the “sigmoid to cusped arcade” signature that was used by Hudson & Sterling (ref? ask Canfield) and later by Canfield, Hudson, & McKenzie (1999) as a proxy to link the sigmoid shape with the probability that a given region would produce an eruption. The upper full-Sun image shows the location of the region on the solar disk; the two insets reveal the appearance of the S-shaped region before erupting into a flare, and the the cusp-shaped loop that is a signature that an eruption has occurred.