ASPs computed on the HD 215152 HARPS data. All are computed with a base model that includes a linear activity model and offsets, as described in Sect. 3.2. They also include three of the four planets. Rows (a), (b), (c), and (d) correspond respectively to leaving out planets at 5.75, 7.28, 10.86, and 25.20 days. Left column: ASPs corresponding to Eq. (7) for different values of τ (blue, orange, green, and red correspond to τ∕T_obs = 10, 1/3, 1/9, and 1/27). Middle column: zoom-in on the maximum peak of the ASP. Right: statistical test on the timescale. When subtracting the 46 day signal with τ = T_obs∕3 (period at which the maximum of the ASP is attained in (d)), we obtain (e) (on the following page), where a coherent 25.2 d signal appears.