Did anyone know that peak flux levels above X15 are estimated? Plus there is dispute about what is the largest solar flare ever recorded since 1976? Is it the 2003/11/04 flare (X45), the 1991/06/01 flare (X17+), or the 1989/08/16 flare (X28.5+)?
Image of 1989/08/14 (5629 (β-γ-δ) is the big region at the southwestern limb/bottom right, 5643 (β-γ-δ) is the big region at the northeastern limb/top left), 2 big regions.
Image source: https://solarwww.mtk.nao.ac.jp/mitaka_solar/wl-fulldisk-photo/calendar/1989/jpg/wl19890814_001.jpg
Discuss anything about large solar flares here.