\begin{table}%t2
\caption{\label{tab2}Observed fluxes and line intensities.} 
%\centering
\small
\begin{tabular}{lrrrr}
\hline\hline
Ion      & $\lambda$(\AA) &$F_{\lambda}$     &  $\Delta(F_{\lambda})$  &     $I_{\lambda}$ \\      
(1)&(2)&(3)&(4)&(5)\\
\hline
PN~3m, $c_{\beta}=0.502\pm0.027$\\
\oii    &  3727   & 373.9    &   58.6   &       517.3     \\
\hg     &  4340   & 50.0   &   3.5 &       58.0   \\
\hb       &  4861   & 100.0    &   4.5  &       100.0    \\
\oiii   &  4959   & 35.4    &   3.8   &   	34.4  \\    
\oiii   &  5007   & 104.2    &   5.2   &   	99.9    \\  
\nii    &  5755   & 1.3    &   0.3   &   	1.1      \\
\hei      &  5876   & 9.1    &   0.3   &   	7.2      \\
\nii    &  6548   & 59.8    &   3.5   &   	42.2      \\
\ha       &  6563   & 412.0   &   6.9 &       290.1   \\
\nii    &  6584   & 142.5    &   4.5   &   	100.0  \\    
\sii    &  6717   & 60.3    &   3.8   &   	41.4      \\
\sii    &  6731   & 44.3    &   3.4   &   	30.4      \\
\hline
\end{tabular}
\end{table}