Variability of LS I +61° 303 optical brightness in V-band for different parts of the data (seasons S1–S11 from top to bottom). The black solid lines correspond to the best fit of the data with function (6). The vertical dashed lines give the phases of the best fit maxima ϕ₀, and the corresponding ±1σ, ±2σ, and ±3σ confidence intervals are shown with varying shades of blue. The vertical scale [0.1, −0.1] is the same in all panels.