\begin{table}%t3
%\centering
\par
\caption{\label{tbl-3}Hyperfine components of the HC$_3$N $J = 2{-}1$ transition.}
\begin{tabular}{ccccr}
\hline \hline \noalign{\smallskip}
\# & $F'$ & $F$ & Weight & \multicolumn{1}{c}{$v_i$,~\ms} \\ 
\hline
1 & 1 & 1 &  0.333 &   $-35~548$.77(2.82)\\[-2pt]  
2 & 1 & 2 &  0.022  &  $-14~167$.97(2.83)\\[-2pt] 
3 & 3 & 2 &  1.867  &  $-1540$.96(2.82)\\[-2pt] 
4 & 2 & 1 &  1.000 &      0.00(2.82)\\[-2pt]    
5 & 1 & 0 &  0.444  &   17~806.60(2.82)\\[-2pt]
6 & 2 & 2 &  0.333  &   21~380.64(2.82)\\ 
\hline
\end{tabular}
\tablefoot{The velocity offsets, $v_i$, are relative to 18.19621694~GHz. 
Data from Lapinov (2008, private comm.) and M\"uller \etal\ (\cite{Muller2005}).}
\end{table}