\begin{table}%t2
%\centering
\par
\caption{\label{TabOrb2}Fitted orbital solution for the GJ~581 
  planetary system: 4 Keplerians.}
\small \begin{tabular}{l l l c c c c}
\hline\hline
\multicolumn{2}{l}{\bf Parameter} &\hspace*{2mm} 
& \bf GJ~581~e  & \bf GJ~581~b  & \bf GJ~581~c & \bf GJ~581~d \\
\hline
$P$ & [days] & & 3.14942 $\pm$ 0.00045 & 5.36874 $\pm$ 0.00019 & 12.9292 $\pm$ 0.0047 & 66.80 $\pm$ 0.14\\
$T$ & [JD-2400000] & & 54716.80 $\pm$ 0.01 &  54712.62 $\pm$ 0.02 & 54699.42 $\pm$ 0.87 & 54603.0 $\pm$ 2.2 \\
  $e$ & & & 0 (fixed) & 0 (fixed) & 0.17 $\pm$   0.07 & 0.38 $\pm$   0.09  \\
  $\omega$ & [deg] & & 0 (fixed)  & 0 (fixed) & --110 $\pm$ 25 & --33 $\pm$  15\\
  $K$ & [m s$^{-1}$] & & 1.85 $\pm$ 0.23 & 12.48 $\pm$ 0.23 & 3.24 $\pm$ 0.24 & 2.63 $\pm$ 0.32\\
  $V$ & [km s$^{-1}$] & & \multicolumn{4}{c}{--9.2082 $\pm$ 0.0002}  \\
  $f(m)$ & [10$^{-14} M_{\odot}$] & & 0.21 & 108.11 & 4.34 & 10.05\\
  $m_2 \sin{i}$ & [$M_{\oplus}$] & & 1.94 & 15.65 & 5.36 & 7.09 \\
  $a$ & [AU] & & 0.03 & 0.04 & 0.07 & 0.22 \\
 % \hline
  $N_{{\rm meas}}$ & & & \multicolumn{4}{c}{119} \\
  {\it Span} & [days] & & \multicolumn{4}{c}{1570} \\
  $\sigma$ (O-C) & [ms$^{-1}$] & & \multicolumn{4}{c}{1.53} \\
  $\chi^2_{\rm red}$ & & & \multicolumn{4}{c}{1.49} \\
  \noalign{\smallskip}\hline
\end{tabular}
\end{table}