Angular covariances of the five-parameter quasar sample. Left: covariance in parallax, V _ϖ (θ). Right: covariance in proper motion, V _μ(θ). The red circles are the individual estimates; the dashed black curves are fitted exponential functions. The bottom panels show the same data as in the top panels, but for small separations only, with errors bars (68% confidence intervals) and running triangular mean values (blue curves).