Rapid oscillations in cataclysmic variables. VII - GK Persei

The discovery of a stable short-period oscillation in the UV light curve of the old nova GK Persei during 1989-91 is reported. The period is consistent with the 351.34-second pulse period seen in hard X-rays, due to the rotation of the white dwarf. In blue light, a quasi-periodic signal appears in the low-frequency wings of the coherent signal. There is evidence for long-term spin-up of the white dwarf; the most probable mean rate is 0.0008 sec/yr.