  To measure the spin period of the white dwarf in V1033 Cas with high
precision, we performed extensive photometry. Observations were obtained over
34 nights in 2017. The total duration of the observations was 143 h. We found
that the spin period of the white dwarf is equal to 563.11633+/-0.00010 s.
Using this period, we derived the oscillation ephemeris with a long validity of
100 years. The spin oscillation semi-amplitude was stable and was equal to
95.5+/-1.3 mmag. This is a very large semi-amplitude of the spin oscillation
among intermediate polars, which have similar and lesser spin periods. This
large semi-amplitude suggests that the system is noticeably inclined. The spin
pulse profile was sinusoidal with high accuracy. This may mean that the spin
oscillation is produced by a single accretion curtain whereas the second
accretion curtain may be obscured by the accretion disc. Despite the large
amount of our observations, we did not detect sidebands. The semi-amplitudes of
the undetected sideband oscillations do not exceed 10 mmag. The absence of
sideband oscillations seems puzzling. We detected the orbital variability of
V1033 Cas with a period of 4.0243+/-0.0028 h and with a semi-amplitude of
55+/-4 mmag. The orbital variability semi-amplitude seems large and also
suggests that the system is noticeably inclined. Using our oscillation
ephemeris and the times of spin pulse maximum obtained in the past, we found
that the spin period is very stable. dP/dt is most probably less than -4 X
10^(-12). This contradicts the assumption that the white dwarf in V1033 Cas is
not spinning at equilibrium. Our spin period and our oscillation ephemeris can
be used for further investigations of the stability of the spin period in V1033
Cas.
