Simulations of the Gaia astrometric measurements. Top panel: absolute shift due to the astrometric microlensing. The green shaded region indicates the span of the photometric event. Bottom panel: projection of the astrometric microlensing displacement along the scan direction. There is no noise included in the simulation. The angle between the scanning direction and the centroid shift δ due to microlensing is colour-coded (see colour bar to the right). The end of the extended mission (currently December 2022) is indicated by the vertical dashed line.