\begin{table}%t2
\caption{\label{T2}Orbital parameters for the planets orbiting {GJ}~876, obtained with a 4-body Newtonian fit to observational data from Keck and HARPS.}
%\centering
 \begin{tabular}{l l c c c}
\hline \hline \noalign{\smallskip}
{Param.}  & {[Unit]} & {$b$} & {$c$} & {$d$} \\
\hline  \noalign{\smallskip}
Date      & [JD]      & \multicolumn{3}{c}{2~455~000.00 (fixed)}  \\ 
$V_{\rm (Keck)}$   & [km~s$^{-1}$]    & \multicolumn{3}{c}{$\phantom{-}0.0130 \pm 0.0004 $}  \\ 
$V_{\rm (HARPS)}$ & [km~s$^{-1}$] & \multicolumn{3}{c}{$-1.3388 \pm 0.0004 $}\\
\hline \noalign{\smallskip} 
$P$          & [day]                & $ 61.067 \pm 0.011 $ & $ 30.258 \pm 0.009 $ & $ 1.93785 \pm 0.00002  $ \\ 
$\lambda$    & [deg]                & $ 35.61  \pm 0.14  $ & $ 158.62 \pm 0.80  $ & $   29.94 \pm 3.30  $ \\ 
$e$          &                      & $  0.029 \pm 0.001 $ & $  0.266 \pm 0.003 $ & $   0.139 \pm 0.032 $ \\ 
$\omega$     & [deg]                & $ 275.52 \pm 2.67  $ & $ 275.26 \pm 1.25  $ & $  170.60 \pm 15.52 $ \\ 
$K$          & [m~s$^{-1}$]                & $ 212.24 \pm 0.33  $ & $  86.15 \pm 0.40  $ & $    6.67 \pm 0.26  $ \\  
$i$          & [deg]                & $ 48.93 \pm 0.97 $    & $  48.07 \pm 2.06 $ & $ 50 $ (fixed)	 \\  
$\Omega$     & [deg]                & $ 0 $ (fixed)         & $  -2.32 \pm 0.94 $ & $  0 $ (fixed) \\
\hline\\[-3mm]
$a_1 \sin i$ & [$10^{-3}$~AU] & $ 1.19$& $0.23$ & $ 1.2 \times 10^{-3} $ \\
$f (M)$ & [$10^{-9}~M_\odot$]& $60.41$ & $ 1.79$ & $ 5.8 \times 10^{-5} $ \\
$M \sin i$ & [$M_\oplus$] & $ - $  & $ - $ 	  & $ 6.3 $ \\
$M$ & [$M_\mathsf{Jup}$] & $ 2.64  $    & $ 0.83  $ 	  & $ - $ \\
$a$          & [AU] & $ 0.211 $ & $ 0.132 $ 	  & $ 0.021 $ \\
\hline
$N_{\rm meas}$        &          & \multicolumn{3}{c}{207}   \\
Span         & [day]                & \multicolumn{3}{c}{4103}   \\
$\sqrt{\chi^2}$     &               & \multicolumn{3}{c}{1.37}   \\ 
rms$_{\rm (Keck)}$         & [m~s$^{-1}$]      & \multicolumn{3}{c}{4.25}   \\  
rms$_{\rm (HARPS)}$        & [m~s$^{-1}$]      & \multicolumn{3}{c}{1.80}   \\
\hline  
\end{tabular}
\tablefoot{Errors are given by the standard deviation $ \sigma $, and $ \lambda $ is the mean longitude of the date. }
\end{table}