Stromgren uvby photometry of the magnetic chemically peculiar stars HR 1643, theta Aur, 49 Cam, and HR 3724

Differential Stromgren uvby photometric observations from the Four College Automated Photoelectric Telescope of four magnetic chemically peculiar stars are used to refine rotational periods and to define the shapes of the light curves. HR 1643 (P=2.73475 d) shows large in-phase variability in all four magnitudes. theta Aur (P=3.6188 d) exhibits large amplitude variations with two components contributing to the minima. For 49 Cam (P=4.28679 d), we probably are observing both polar regions and much of the surface. The values for HR 3724 (P=33.984 d) confirm Wolff's result that the main variability is in v.