\begin{table}%t1
\caption{Orbital and physical parameters.}
\label{orbparam}
%\centering
\par
\begin{tabular}{l l c }
\hline\hline
\multicolumn{2}{l}{Parameter} & Gl~581 b \\
\hline
$P$                 & [days]                 & \periode~$\pm$~\eperiode \\
$T$                 & [JD-2~400~000]   & \T~$\pm$~\eT \\
$e$                 &                             & \e \\
$V$                 & [km~s$^{-1}$]    & \V~$\pm$~\eV \\
$\omega$      & [deg]                  & \w \\
$K$                 & [m s$^{-1}$]      & \K~$\pm$~\eK \\
$a_1 \sin{i}$  & [10$^{-3}$ AU] & \aunsini \\
$f(m)$             & [10$^{-9} ~M_{\odot}$] & $0.1354\times10^{-2}$ \\
$m_2 \sin{i}$ & [$M_{{\rm Earth}}$] & \mdeuxsini \\
$a$ & [AU]     & \demiaxe \\
\hline
$N_{{\rm meas}}$ & & 20 \\
$\it Span$ & [days] & 440\\
$\sigma$ (O--C) & [m~s$^{-1}$] & \sigmaOmC \\
\hline
\end{tabular}
\end{table}