Context : Aims : We model the photometry of RS CVn star $ σ $ Geminorum to obtain new information on the changes of the surface starspot distribution , i.e. , activity cycles , differential rotation and active longitudes . Methods : We use the previously published Continuous Periods Search-method ( CPS ) to analyse V-band differential photometry obtained between the years 1987 and 2010 with the T3 0.4 m Automated Telescope at the Fairborn Observatory . The CPS-method divides data into short subsets and then models the light curves with Fourier-models of variable orders and provides estimates of the mean magnitude , amplitude , period and light curve minima . These light curve parameters are then analysed for signs of activity cycles , differential rotation and active longitudes . Results : We confirm the presence of two previously found stable active longitudes , synchronised with the orbital period P _ { \mathrm { orb } } = 19 \aas@@fstack { d } 60 and find eight events where the active longitudes are disrupted . The epochs of the primary light curve minima rotate with a shorter period P _ { \mathrm { min, 1 } } = 19 \aas@@fstack { d } 47 than the orbital motion . If the variations in the photometric rotation period were to be caused by differential rotation , this would give a differential rotation coefficient of \alpha \geq 0.103 . Conclusions : The presence of two slightly different periods of active regions may indicate a superposition of two dynamo modes , one stationary in the orbital frame and the other one propagating in the azimuthal direction . Our estimate of the differential rotation is much higher than previous results . However , simulations show that this can be caused by insufficient sampling in our data .