\begin{table}%t3
 \caption{\label{tab3}HC$_3$N peak optical depths corrected for incomplete continuum source coverage (see Sect.~4.1.1). $f_{\rm c}$ is the source covering factor, $\nu$ denotes the redshifted frequency.}
\par
%\centering
\par
\begin{tabular}{ccc}
\hline \hline 
  Line & $f_{\rm c} = 0.3$  & $f_{\rm c}= 0.2 \times \nu/26$~GHz)$^{0.5}$ \\
\hline
HC$_3$N $J =3 \leftarrow2$     & $0.0239\pm0.0046$  &  $0.0462\pm0.0089$ \\
HC$_3$N $J =4 \leftarrow3$     & $0.0482\pm0.0093$  &  $0.0807\pm0.0156$ \\
HC$_3$N $J =5 \leftarrow4$     & $0.0721\pm0.0106$  &  $0.1084\pm0.0158$ \\
HC$_3$N $J =6 \leftarrow5$     & $0.1000\pm0.0221$  &  $0.1367\pm0.0302$ \\
HC$_3$N $J =7 \leftarrow6$     & $0.0837\pm0.0174$  &  $0.1059\pm0.0219$ \\
\hline
\end{tabular}
\end{table}