Astrometric analysis of 339 reliable sources, common between 2015 and 2018, left and right data. Top: shift of stars, measured in the right (green crosses) and left (purple pluses) data vs their K magnitudes. Middle: total error (purple pluses) and photometric error (green crosses) on the positions of the detected sources, averaged between the left and right data vs their K magnitudes. Bottom: shift of a star over its total error () vs its K magnitudes, colour-coded by Δμ_(R, L). The horizontal black lines show the average value for all 339 sources.