Summary statistics for the 2 million sources in the primary data set of Gaia DR1: a) density of sources; b) number of good CCD observations per source; c) excess source noise. These maps use an Aitoff projection in Galactic coordinates, with origin l = b = 0 at the centre and l increasing from right to left. The mean density (a) and median values (b and c) are shown for sources in cells of about 0.84 deg². A small number of empty cells are shown in white.