Notes. For each dSph we include the derived position on the sky (α, δ), parallax ϖ, PMs (μ_α*, μ_δ), and the elements of the covariance matrix ϵ_ϖ, ϵ_μα*, ϵ_μδ and correlation coefficients C. The last two columns list the number of stars and the magnitude limit used for the determination of the astrometric parameters, respectively. The (α, δ) listed here are determined from stars with five-parameter solutions, and hence these coordinates might not provide the most accurate estimate of the centre of the dSph because of incompleteness in the spatial coverage of such solutions (see e.g. Fig. 2). For the orbital integrations in Sect. 6 we therefore used (α, δ) sky coordinates from the literature.