Panel a: show GLS periodogram of the combined HIRES (green diamonds) and CARMENES (red circles) data for GJ 15 A, while panels b and c show separate GLS periodograms for the HIRES, and CARMENES data, respectively. Panels d−f show the best-fit models to the combined and the separate data sets. The HIRES data strongly suggest several periodicities, most notable at a period of 11.44 d, which is associated with the putative planet GJ 15 Ab, a period of 45.42 d, attributed to stellar activity, and a few long-period peaks, which disappear when we fit a linear trend to the data. A GLS power spectrum to the 92 CARMENES RVs, however, does not show significant peaks, which is also the case for more recent HIRES RVs (see Fig. 11, bottom panel). No valid Keplerian model with a period of 11.44 d can be fitted to the post-discovery HIRES and CARMENES data, casting doubts on the existence of GJ 15 Ab. The available data for GJ 15 A are dominated by the early HIRES RVs, and thus the putative planetary signal is still detected in the combined data set.