The photometric periods of the intermediate polar EX Hydrae.

Five-color photometry of the dwarf nova EX Hya during its quiescent state revealed that no independent modulations of the optical light are persistent other than the 98-min binary orbital period and the 67-min spin period of the white dwarf. No indication could be found for additional photometric periods claimed previously, in particular, a possible period of 46.2 min. However, a transient modulation with P = 28.4 min was observed which may be explained as a beat of the 67-min period and half the orbital period, and which gives some evidence that a significant orbital-phase-dependent amplitude modulation of the 67-min variation may occur in EX Hya. The observations confirm that the center of the optical eclipse wanders back and forth in time by + or - 20 s as a function of 67-min phase, suggesting that the eclipsed optical source is locked to the white dwarf and centered at a radial distance of about 1.5 x 10 to the 9th cm. The U-B color variation supports the presence of a Balmer emission component which shows a more pronounced 67-min modulation than the remainder of the light and which is less strongly eclipsed.