Long-term variations in the brightness UBVRI (Johnson system) of ρ Cas between 1965 and 2017. The arrows and the dates at the top mark eruptive episodes. Data points at JD ∼ 24 58000 are observations by EJvB. Between the V and B light curves the mean quasi-periods are shown with their σ for some selected time intervals. Their mean durations are represented by the length of the bars. The number of cycles used are bracketed. A correlation between the trend of the mean quasi-periods and the (B − V) is obvious: they increase and decrease when the (B − V) becomes red and blue, respectively (while V is almost constant, B shows a cyclic fainting and brightening before and after an eruption). The eight B-data points represented by circles are based on a (V − R)/(B − V) relation when no B observations were made.