Large flare on the red dwarf star UV Ceti

ATTEMPTS to measure radio emission occurring simultaneously with the sporadic optical flares on the red dwarf dMe type stars have been hindered by the rarity of large flares. Apart from one case of a flare with an unusually long duration and a peak magnitude of 1.7 (ref. 1) the correlation so far established has been limited to flares of about 1 mag or less 2,3 . On October 11, 1972 we were able to obtain simultaneous radio and optical recordings of an unusually large flare on the star UV Ceti (L726–8AB), during which the apparent magnitude of the star increased by more than 4.55 mag.