The Algol type variable RZ Cas has a period of 1.195247 days according to the GCVS. These light curves cover a time period of just under 6 hours around the time of its primary eclipse. The phases were calculated using the GCVS elements. If the eclipses were occuring as predicted by the GCVS elements, then the primary eclipse would be centred on phase 0. However, in the 1993 light curve it is centred at around phase 0.014 (approx 20 minutes late). By 1998, this discrepancy had more than doubled.