Pre- and post- NZP correction RV scatter for three CARMENES targets that we consider as “RV-quiet” stars. The top two panels are for GJ 109, the middle two show GJ 172 and the bottom two GJ 4063. The NZP correction leads to lower rms scatter for almost all RV-quiet stars in the CARMENES sample (see Fig. A2). Note that the mean measurement error increases somewhat due to the propagation of the error of the NZP correction.