  BS Cir is a representative of moderately cool magnetic chemically peculiar
stars which displays very strong light variations in Stroemgren index c1
indicating large changes in the height of the Balmer jump. We present two-spot
model of light variations fitting successfully all of nine light curves
obtained in the spectral region 335-750 nm. We also discuss the nature of the
observed variations of intensities of Fe, Cr, Ti, Si, Mg and RE spectral lines
and possible mechanisms matching the observed light variations. It was
confirmed that the observed period of BS Cir 2.204 d is rising with the rate of
dP/dt=5.4(4)x10^-9. The found minor secular changes in the shape of light curve
should be compatible with the period changes caused by precessional motion due
to magnetic distortion of the star.
