Variation of the magnification above baseline A − 1 (black curve) and the centroid shifts δ_mic (mas; red curve) and θ₂ (mas; blue curve) as a function of time (d) for the two fictitious microlensing events described in Sect. 3.5. The events differ only in that u₀ = 0.6 and u₀ = 1.6 for the left- and right-hand panels, respectively. The vertical dashed lines in each panel indicate when an event switches between unresolved and partially-resolved microlensing based on the median Gaia spatial resolution of ~103 mas. The dotted curves indicate the photometric (G-band) and astrometric (along-scan) precisions for a single observation with black, red and blue colours corresponding to A − 1, δ_mic and θ₂, respectively.