Detection of optical oscillations of the intermediate polar V709 Cassiopeae (RX J0028.8+5917)

We report detection of low-amplitude optical oscillations at periods of 312.77 s and 317.94 s of the intermediate polar V709 Gas. Within the accuracy of measurement these periods agree with the X-ray period reported by Motch et al. (1996) and refined by Norton et al. (1999) and its synodic counterpart if we specify an orbital period of 5.4 h, which is one of the two possible orbital periods reported by Motch et al. (1996). The oscillation at a period of 317.94 s has the strong first harmonic which is evidence for the nonsinusoidal pulse profile of this oscillation. The data folded at a period of 317.94 s reveal a double-peaked pulse profile of this oscillation. which is highly variable from night to night. A weak periodic signal corresponding to the first harmonic of the oscillation at a period of 312.77 s is also detected in the lightcurves of V709 Cas.