Top: convergence of the mean values of secular angles, longitude of node in red and longitude of perihelion in blue, for Hobson family members in the base model with planetary perturbations alone. The time at abscissa extends to the past, and the ordinate shows the difference of the respective angle with respect to the orbit of (18777) Hobson. The reference frame is defined by the invariable plane of the Solar System. Bottom: value of target function ΔV from Eq. (1) computed for the orbits shown in the top panel. The gray horizontal line indicates 5 m s⁻¹, the estimated escape velocity from the family parent asteroid (Sect. 3). Left panels: 12 members with H ≤ 17.75. Right panels: all Hobson members on multi-opposition orbits. The gray Gaussian curve in the top panels schematically indicates thesolution 365 ± 67 kyr for the age of the Hobson family from Rosaev & Plávalová (2017).