Generalised Lomb-Scargle periodogram of the HARPS and HARPS-N data of BD-11 4672 (top panel) and the residuals obtained after removing the n_s−signals best-fit solution (second to fourth panels). In each panel, the periodogram’s most significant frequency is identified by a vertical dotted red line and labeled by its corresponding period, while the horizontal solid, dashed and dotted lines respectively identify the 10, 1, and 0.1% FAP levels.