High-speed photometry of three dwarf novae during eruption

Eruptions in RX And, SY Cnc, and KT Per, which are dwarf novae of the Z Cam type, have been observed with a high-speed photometer. White-dwarf pulsations were observed with periods of 24.6 s in SY Cnc and 26.7 s in KT Per, bringing the total to five Z Cam stars in which such pulsations have been observed. RX And did not exhibit pulsations, but its eruption was small, being only a 1.9 mag increase in brightness. The evidence suggests that five distinct pulsation periods, with separations of 0.10 s, simultaneously coexist in the light curve of KT Per. In intensity units, the flickering activity in RX And increased in amplitude during its eruption, which is interpreted as an increase in the intensity of the bright spot on the disk of gas around the white dwarf. Subject headings: pulsation - SS Cygni stars - white dwarf stars