Uncertainties on the astrometric parameters vs. G for Gaia data releases 1–3 and for the future releases Gaia DR4 and Gaia DR5. The panels show from top to bottom the uncertainties in parallax, proper motion in Right Ascension, and proper motion in Declination. The uncertainties for Gaia DR1 refer to the Tycho-Gaia Astrometric Solution and are shown in the form of density maps, with lighter colours indicating a higher density of sources. The two distinct low-uncertainty elliptical regions in the Gaia DR1 proper motion uncertainties are due to stars for which the HIPPARCOS and Gaia positions could be combined to derive proper motions over a 24-year time baseline. The proper motion uncertainties for Gaia DR3, based on only a 34 month time baseline are comparable or even slightly better.