Winzer (1974) discovered HR 2258 was a photometric variable
and derived a period of 1.0785 days. It is a sharp-lined star with 
(Wolff & Preston 1978). Adelman (1975,
1982) discovered it has a definite 
5200 broad, continuum
feature as well as modest 4200 feature. An abundance analysis by
Lopez-Garcia & Adelman (1994) showed that most of its iron
peak elements are 10 times solar while its rare earths are typically 1000
times solar.
I obtained 110 observations of HR 2258 (10 in year 2, 12 in year 3, 8 in year 4, 34 in year 5, and 46 in year 6). A periodogram analysis of the y values shows that the period is 15.033 days. Winzer's period is an alias of this period. Examination of the u data shows that the extrema of the values occur with this period which is also much more consistent with the sharp-lined nature of the star. Adding a constant to Winzer's V data and comparing it to the y data indicates that the period should be 15.0305 days. The scatter in the uvby data with this period is slightly greater than found for the correct periods of many magnetic CP stars with FCAPT data.
The zero point was found by adjusting Winzer's value. It is an average of those for the four colors and needs to be better defined by obtaining additional photometry with phases close to it.
The adopted ephemeris is
Figure 2 (click here) show that the variability is roughly in phase in all four
colors with amplitudes of 0.06 mag in u, 0.035 mag in b, and 0.03 mag
in v and y. The light curves are asymmetric with the fall from maximum
being faster than the rise from minimum.