SIMBAD references

Four College Automated Photoelectric Telescope differential Stroemgren uvby photometric observations of four magnetic chemically peculiar stars are presented. One of our comparison stars was also found to be variable. Observations of the sharp-lined Si star HD 11187 are best described as representing a constant star. HD 15144 was also constant photometrically. However, its comparison star HD 14940 is definitely variable. But we were not able to find a period. It may be a δ Scu star. Our observations of 20 Eri and the uvby values of Renson & Manfroid show definite differences in the shapes of the light curve which suggest that this star may be undergoing a precession of its rotational axis. When we refined the period by using the minima we find a value of 1.92893 days. We refined Winzer's period of the relatively large amplitude variable HR 8933 to 2.86031 days. In v and b there are definite indications of a weak submaximum within the broad minimum.