Phase-folded RV curves of the Be star and its companion in the MWC 656 binary system, using the best-fit orbital period. RV measurements and uncertainties of the Be star (circles) and the companion (squares) are shown with colour-coded markers corresponding to the instrument used. Maximum-likelihood orbital models derived from RV fitting are overplotted for the Be star (pink) and the companion (green) with thick lines. Thin lines show orbital models for random samples from the posterior to illustrate uncertainties in the inferred parameters. The grey dotted line shows the inferred systemic velocity. Star symbols indicate the predicted orbital phases and velocities of the four HST/STIS FUV observations based on the fitted orbit.