Slides of presentation delivered at the European Astronomical Society (EAS) Annual Meeting in Lausanne, Switzerland, on 29 June 2026. Includes descriptions of the Gaia DR4 pre-release material and figures showing the astrometric performance of very-bright stars. https://great.ast.cam.ac.uk/Greatwiki/GreatMeet-PM19
J. Sahlmann (Mon,) studied this question.