Optical flares on the RS CVn binary II Peg.

During 57.4 hr of optical monitoring in the Johnson U- and B-bands of the RS CVn binary II Peg, 10 flares were detected. The absolute energies of these events are in the range 1-180 x 10 exp 33 erg. This implies a flare activity in the U-band of 0.17 flares per hour, compared with 0.12 flares per hour from UV C IV data. A double power-law distribution is required to fit the cumulative flare-frequency distribution of the U-band flares.