Consistency of the period of signals in the solar data. (a and b): value of the χ² defined in Eq. (6) for the solar HARPS-N RV data as a function of t₀ for τ = 365 (=T_obs ∕3) days (a) and τ = 121 (=T_obs ∕9) days (b). (c and d): value of the semi-amplitude as a function of t₀ for τ = 365 (=T_obs ∕3) days (c) and τ = 121 (=T_obs ∕9) days (b). Grey areas correspond to 1 σ uncertainties greater than 30 cm s⁻¹. (e and f): in blue, position of the mode of the ASP between frequencies represented in grey as a function of t₀, as defined in Sect. 2.3. Computed for τ = 365 (=T_obs ∕3) days (c) and τ = 121 (=T_obs ∕9) days (d).