SPATIAL RELATIONS BETWEEN PREFLARES AND FLARES

We have conducted an initial search for discrete preflare brightenings as observed in soft X-radiation by Yohkoh. The Yohkoh images allow us to identify, to within a few are seconds, the location of a preflare event relative to the succeeding flare. Our initial motivation in this study was to search for early coronal brightenings leading to flare e ffects, as had been suggested by earlier studies; thus we concentrated on Yohkoh limb events. We find no evidence for such early coronal bri ghtenings. Between 15% and 41% of the 131 suitable events matched our criteria for preflare brightening: the same active region; brightening within one hour of the flare peak; preflare brightness less than 30% of the flare peak. In the great majority of the preflare cases, we fou nd that physically separate nearby structures brightened initially. Of ten these structures appeared to share a common footpoint location wit h the flare brightening itself. In a few cases the preflare could have occurred in exactly the same structure as the flare.