VZ Pup & 23.175 & 0.50 & 71\
SW Vel & 23.428 & 0.53 & 62

![ Normalized variations of $H$-band light curves and radial velocity curves for nearby Cepheids with $P\simeq 20$ days [@Groenewegen-2013]. Fitted template curves and the $\pm 1\sigma$ ranges are indicated by solid and dashed curves, respectively. \[fig:fit\_combined\]](fig4.ps){width="0.98\hsize"}

![ Velocity amplitude versus amplitude of $H$-band light curves for nearby Cepheids with $P\simeq 20$ days [@Groenewegen-2013]. Object names and dataset used are stated in the text. The slope of the solid line was obtained as the average of $A_{\rm RV}/A_{H}$ values, and its standard deviation $\sigma$ is indicated by the dotted lines. \[fig:comp\_amp\]](fig5.ps){width="0.98\hsize"}

We estimated the $H$-band amplitudes and the pulsation phases of our target Cepheids in individual spectroscopic observations by fitting seventh-order Fourier series to the light curves. The velocity amplitude $A_{\rm RV}$ was estimated combining the $A_{H}$ and the amplitude ratio, and the mean velocity was obtained by shifting the velocity curve template multiplied by the predicted amplitude. When two or more measurements were available, the estimated mean velocities of each object were averaged. Figure \[fig:phase\_cor\] shows the template, which is vertically shifted to fit the measured values. Note that the amplitudes are predicted based 