2001A&A...366..891K

We report detection of low-amplitude optical oscillations at periods of 312.77 s and 317.94 s of the intermediate polar V709 Cas. Within the accuracy of measurement these periods agree with the X-ray period reported by Motch et al. (1996A&A...307..459M) and refined by Norton et al. (1999A&A...347..203N) 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. (1996A&A...307..459M). 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.