\begin{table}%t3
\caption{Electron temperatures and densities.}
\label{temperature}
%\centering
\par
\begin{tabular}{lllllll}
\hline
\hline
\multicolumn{1}{c}{Object} & \multicolumn{1}{c}{$N_{{\rm e}}~   ({\rm cm^{-3}})$}  & 
\multicolumn{1}{c}{$N_{{\rm e}} ~({\rm cm^{-3}})$}  & 
\multicolumn{1}{c}{$N_{{\rm e}} ~ ({\rm cm^{-3}})$}  & 
\multicolumn{1}{c}{$T_{\rm e}~({\rm K})$}             & 
\multicolumn{1}{c}{$T_{\rm e}~({\rm K})$}            & 
\multicolumn{1}{c}{$T_{\rm e}~({\rm K})$}   \\               
& \multicolumn{1}{c}{\ion{S}{ii}} & \multicolumn{1}{c}{\ion{Cl}{iii}} & \multicolumn{1}{c}{\ion{Ar}{iv}} & \multicolumn{1}{c}{\ion{N}{ii}}
& \multicolumn{1}{c}{\ion{O}{iii}} & \multicolumn{1}{c}{\rm Bal}  \\       
\hline
\object{NGC~1535} &                              & 	                         &$\phantom{1}1672 \pm  101$ &                   & $11~765 \pm 55$           &$\phantom{1}8990 \pm  91$  \\
\object{NGC~2438} & $\phantom{1} ~~ 143 \pm 71$  &                              &$\phantom{1}2206 \pm 870$  & $11~262 \pm 360$ &  $11~192 \pm 64$          &                             \\ 				  
\object{NGC~2440} &   $\phantom{1}1807 \pm 83$ & $\phantom{1}4898 \pm2097$&$\phantom{1}2525 \pm 122$  & $11~670 \pm 64$  & $14~569 \pm 22$           &$12~693 \pm 307$            \\
\object{NGC~3132} & $\phantom{1} ~~ 637 \pm 52$  & $\phantom{1}1289 \pm 706$  & $\phantom{1}2265 \pm 856$ & $10~454 \pm 78$  &$\phantom{1} 9390 \pm 112$&		               \\
\object{NGC~3242} & $\phantom{1}1016 \pm 255$  &$\phantom{1}2531 \pm 1227$&$\phantom{1}3665 \pm  141$ &  	           &$ 12~140 \pm 31$          &  $\phantom{1} 9444 \pm 41 $  \\    
\object{NGC~6302} &  $\phantom{1}2183 \pm 436$ & $13~016 \pm 4640$	 &   $10~630 \pm  137$        &$ 14~381 \pm 310$ &$ 17~927 \pm 61$ 		&                               \\
\object{NGC~7009} & $\phantom{1}3778 \pm 227$  & $\phantom{1}5168 \pm 384$  &$\phantom{1}5589 \pm  128$ &$10~128 \pm 120$  &  $ \phantom{1}9969 \pm 105$&   $\phantom{1}8690 \pm 32$ \\
\hline
\end{tabular} 
\end{table}