Capture probability of Saturn in secular spin-orbit resonance with ϕ₃ as a functionof its primordial obliquity. For each initial obliquity (401 values between 0 and 60°), 720 values of initial precession angle are uniformly sampled in [0, 2π) and propagated forwards in time starting from − 4 Gyr and until every trajectory has reached the resonance. This experiment is repeated with two different migration laws for Titan (see labels). The result is virtually independent of the value chosen for λ. The fractionof captured trajectories (coloured curves) is compared to the perfect adiabatic case (black curve) computed with the analytical formulas of Henrard & Murigande (1987).