The photometric variations of 25 Sex, spectral type B9p Si(Sr,Cr) (Cowley et al. 1969) have been analyzed from observations obtained within the framework of the Long-Term Photometry of Variables project at ESO, most recently by Manfroid & Renson (1994). Their comparison star is HD 90882. Their data set consists of 160 uvby values obtained over a period of some 4300 days.
Their ephemeris is HJD(
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My FCAPT observations begin just after their data set was completed. There are 123 uvby values over an interval of some 1100 days. A periodogram analysis of the u values showed that the most likely period was 4.3790 days in agreement with Manfroid & Renson.
Figure 2 (click here) shows the FCAPT data plotted with their ephemeris. This diagram, which is very similar to that of Fig. 5 of Manfroid & Renson, confirms their results. The origin of the ephemeris appears to be minimum light for u. Those for the other three magnitudes appear to be slightly offset. Although the variations for b, v, and y are crudely in phase, they are quite different from that for u. The amplitudes of variations are 0.07 mag for u, 0.03 mag for v, 0.04 mag for b, and 0.025 mag for y. There appear to be two spots with different energy distributions.