\begin{table}%t9
%\centering
\par
\caption{Electron temperature indicators in NGC~40.}\label{t9}
%\begin{flushleft}
\begin{tabular}{lcccc}
\hline
\hline
Ion & Ioniz. & Lines& Observed & $T_{{\rm e}}$\\
 & pot. (eV)& used &ratio  & (K) \\
\hline
\ion{[N}{ii]} & 14.5 & 5755/6584 & 0.0078 & 7500\\
\ion{[S}{iii]} & 23.3 & 6312/18.7 & 0.0145 & 7800 \\
\ion{[Ar}{iii]} & 27.6 & 7136/8.99 & 0.488 & 7000\\
\ion{[O}{iii]} & 35.1 & 4363/5007 & 0.0062 & 10~500\\
\ion{[O}{iii]} & 35.1 & 5007/52  & 2.15 & 8000\\
\ion{[Ne}{iii]} & 41.0 & 3868/15.5 & 0.295 & 8400\\
\hline
\end{tabular}
\end{table}