\begin{table}%t1
  \caption{Close approach circumstances of comet 79P/du-Toit-Hartley's orbit to that of Mars.}
\label{tab:79Pclo}
\small%\centerline
{
\begin{tabular}{lrrrrr}
\hline \hline
                & $L_{\rm S}$&   $\Delta$  & ${v}_{\rm imp}$     & \multicolumn{2}{c}{Radiant (J2000)}\\
                &  (deg)  &     (AU)    & (km ${\rm s}^{-1}$)   &   $\alpha$(deg) &  $\delta$(deg)  \\\hline
$L_{1}$   & 173.7   &    0.0340   &       14.3              &    93.2    &   +18.4     \\
$L_{2}$   &  44.2   &    0.0547   &       14.3              &    119.7   &     +26.8     \\  
\hline
\end{tabular}}
\medskip
These were calculated as in \cite{ChristouBeurle99} using the
cometary orbit in Table~\ref{tab:79Porb} and osculating orbital
elements of Mars's orbit at the same epoch from HORIZONS. 
Here $\Delta$ is the orbit-to-orbit minimum distance, ${v}_{\rm imp}$ the velocity
at the top of the Martian atmosphere and $\left(\alpha, \delta \right)$ the 
right ascension and declination of the theoretical radiant in the 
usual Earth-based (i.e.~not Mars-based) reference frame.
\end{table}