Relative astrometry all sources in RA and Dec offsets. Left panel: Relative astrometry of all sources to the primary star (mass ratio = 0). Right panel: Relative astrometry of all the sources to the barycentre when the mass ratio = 1. The positions of all sources of the first epoch are calibrated to the origin, so the positions of the later epochs are subtracted by the positions of the first epoch. The candidate is shown by the triangle and square markers with the epoch 2021-12-02 in orange and the epoch 2023-03-03 in green. The sources are labelled with the same number in Fig. 1, using the same colour convention for epochs. The blue line is the trajectory of a static background star evolving from 2018-11-15 and the two points on the track are the positions on 2021-12-02 and 2023-03-03 calculated by the proper motion and parallax reported in Gaia.