Radial velocity time series (unbinned data). The error bars depict the internal measurement errors ΔRV_i, i.e. not including jitter. LC (green open circles) and VLC (blue open diamonds) data are displayed with their measured offsets. Jumps in the curves indicates the difference between the measured (Sect. 3.5) and fitted (Sect. 4) LC-VLC offset. HARPS data are in red filled circles. The solid lines indicate significant models, while dashed lines illustrate less or non-significant alternative models. All models include secular acceleration. Model curves are shown for β Hyi (trend and long-period sinusoid, see text for discussion), and HR 506 (sinusoid).