Astrometric precision of the DR4 PSF data compared to Gaia coordinates of over 4 million sources. Main panel: distribution of the sources colour-codded by the absolute value of the proper motion |µ| obtained from the Gaia data. The contours represent 1σ (cyan), 2σ (yellow), and 3σ (green) of the distribution. The histograms show the respective distributions for each axis with the dashed lines corresponding to 1σ, 2σ, and 3σ. The histogram labels show the respective distribution’s median and σ.