Examples of initial conditions for Hydra. Top row: orbital variation in the semi-major axis (left) and eccentricity (right) of Hydra according to the adopted criteria. The initial conditions are a_C ∕R_P= 4, e_C = 0.001, Ω_C ∕n_C = 2, A = 10, and Δt_P = 6 s. Bottom row:time variation in the mean-motion ratio (left) and ϕ_6∕1 = 6λ − λ_C − ϖ_C − 4ϖ (right) for two values of Δt_P, namely, 6 s and 60 s. We note that, for Δt_P = 60 s, ϕ_6∕1 librates witha large amplitude around 0°. For Δt_P = 6 s, all critical angles associated with the 6/1 MMR circulate.