\begin{table}%t2
\caption{Orbital elements of comet 21P/Giacobini-Zinner.}
\label{tab:21Pelem}
%\centering
\par
\begin{tabular}[htbp]{ccc}
\hline\hline
Year 			& 	1596	& 	2005\\
\hline
Date (Julian Day) 	& 2~304~043.5	& 2~453~557.5	\\
$a$ (au)		& 3.50	& 3.53\\
$e$			& 0.701	& 0.706\\
$i$ ($ ^{\circ}$)		& 33.7	& 31.8	\\
$\Omega$ ($ ^{\circ}$)	& 206.8& 195.4	\\
$\omega$ ($ ^{\circ}$)	& 168.43& 172.5	\\
\hline
\end{tabular}
\end{table}