GLS periodograms for Gl 393. Panel a: HIRES data, and Panel b: HIRES data residuals after pre-whitening the highest peak with a Keplerian fit. Panels c and d: HARPS data (panel descriptions as in those for HIRES). Panels e and f: CARMENES VIS channel data. Panels g and h: combined data set. FAPs as in Fig. 3. Vertical dashed linesmark the highest peak found in the combined data (purple) and the highest peak after pre-whitening the GP (orange).