Summary statistics for full quasar sample. Top: number of visibility periods used. Middle: σ_{5d,  max}. Bottom: unit weight error u. These maps use a Mollweide projection in equatorial (ICRS) coordinates, with origin α = δ = 0 at the centre, and α increasing from right to left. The values are calculated in spherical cells of about 1.8 × 1.8 deg². Empty cells as well as cells with sources no more higher than ten are shown in dark blue.