\begin{table}%t5
\caption{Orbital elements for 2 SBs in NGC~2420.
\label{elem2420}}
%\centerline
 $${
\begin{tabular}{lr@{.}lr@{.}lr@{.}l}
\hline\hline\noalign{\smallskip}
 Element & \multicolumn{2}{c}{173} & \multicolumn{2}{c}{250}  \\
\hline\noalign{\smallskip}
$P$ [d]                 &  1479&0    & 1403&6    \\
                        &     9&1    &    3&5    \\
$T$ [HJD-2~400~000]       & 42213&     & 45258&    \\
                        &    25&     &   64&     \\
$e$                     &  0&433     &    0&08   \\
                        &   &050     &     &03   \\
$\gamma$ [km s$^{-1}$]  & 73&71      &   78&20   \\
                        &   &17      &     &13   \\
$\omega$ [$^{\circ}$]   &  187&9     &  141&     \\
                        &    8&1     &   16&     \\
$K$ [km s$^{-1}$]       &    4&15    &    6&90   \\
                        &     &18    &     &21   \\
$f$($m$) [$M_{\odot}$]    &  0&0080    &  0&0473   \\
                        &   &0017    &   &0047   \\
$a\sin$i [Gm]           &   76&1     &  132&7    \\
                        &    5&8     &    4&6    \\
$\sigma \rm (O{-}C)$ [km s$^{-1}$] & 0&49  &   0&51    \\
$n_{\rm obs}$ & \multicolumn{2}{c}{25} & \multicolumn{2}{c}{26} \\
\hline
\end{tabular}}
$$
\end{table}