Ephemeris of 2002 WC₁₉ calculated with NIMA (Desmars et al. 2015) using positions from classic astrometry (upper panels), and including astrometric position obtained from a stellar occultation (yellow dots in the lower panels). This was a single-chord event, with two possible solutions, therefore two yellow dots are shown in the lower right panel because the northern and southern solutions were both used to calculate this orbit. The black linesrepresent the difference between NIMA and JPL 06 ephemerides, and the gray regions are the 1σ uncertainties from NIMA. The uncertainty is clearly reduced when the astrometric positions derived from a stellar occultation are included.