Contour plots showing the time taken for the rms Δϕ to reach 2π as a function of dispersion in position σ_r and velocity σ_v of the Gaussian clump of Equation (13) for (left and middle panels) Keplerian and (right panel) logarithmic potentials. The left and right panels have been computed by direct simulation, whilst the middle panel uses the analytic formula of Equation (14). All the panels refer to the case of a 10¹⁰ M_☉ association, which is placed on an orbit with μ_r = 200 kpc and μ_v = 150 km s⁻¹. This is tailored for the case of dispersal of an assemblage of dwarf galaxies in the outer parts of the halo of a galaxy like M31.