Four maps of Gaia data density at various proper-motion and parallax levels. The proper-motion and parallax values of each sub-plot are indicated in the titles, with proper motions given in milliarcseconds per year and parallax in milliarcseconds. Maps are plotted in a Mollweide projection in Galactic coordinates, with l increasing to the left, north being up, and the Galactic centre in the middle. Vertical and horizontal grid lines show spacings of 60 and 30 degrees in l and b, respectively.