Megaflare: The Largest Ever Seen?

October 29, 2003

TRACE (Transition Region and Coronal Explorer) observed its first official "megaflare" on 28 October 2003. Active Region 10486 had been treating us to multiple large flares in the days before as a result of its magnetic complexity (AR10486 is the region southward of the MDI high-res field of view shown by the white square in the magnetogram), so we were expecting more fireworks! And then there was this enormous flare, first labeled as X17, later upgraded to X20; this may be the biggest flare on record.

http://vestige.lmsal.com/TRACE/POD/TRACEpod.html