\begin{table}%t1
%\centering
\par
\caption{\label{journal} Journal of our red spectroscopic observations of WR~20a. The first and second columns provide the heliocentric Julian date (in the format HJD$ - 2~450~000$) and the orbital phase computed using the ephemeris of Bonanos et~al.\ (\cite{bonanos}). Phase $\phi = 0.0$ corresponds to the "primary eclipse'' with the slightly less massive star in front. Columns~3 and~4 respectively indicate the grism used for the observation (see text) and the equivalent width of the H$\alpha$ emission line as integrated between 6499 and 6646~\AA\ (see Sect.~\ref{lpv}).}
\begin{tabular}{c c c c}
\hline\hline
Date & $\phi$ & Grism & {\it EW}(H$\alpha$)   \\
     &        &       &(\AA) \\
\hline
3032.766 & 0.094 & \#6 & 33.6 \\
3033.762 & 0.364 & \#6 & 28.7 \\
3034.760 & 0.635 & \#6 & 31.4 \\
3036.762 & 0.178 & \#6 & 31.4 \\
3037.784 & 0.456 & \#6 & 35.1 \\
3038.765 & 0.722 & \#6 & 31.9 \\
3039.772 & 0.995 & \#6 & 42.2 \\
3040.760 & 0.263 & \#6 & 31.4 \\
3041.747 & 0.536 & \#6 & 40.6 \\
3042.734 & 0.798 & \#6 & 31.0 \\
3179.472 & 0.895 & \#5 & 26.6 \\
\hline
\end{tabular}
\end{table}