\begin{table}%t4
\par
\caption {\label{tab: parameter values density and size}Observed and calculated values to obtain relevant geometrical and physical parameters of the photoionised gas 
(Sect.~\ref{par:flat},~\ref{par:density_size}).}
%\centering
\par
\begin{tabular}{llllll}
\hline \hline
                                                       & &   A   &  C1  &  C2  &  C3  \\
\hline
{\bf observed values}&&&&&\\
$L_{\rm cont}$ & $10^{37} {\rm ~ergs / s}$         & 1.38  & 1.05  & 1.06  & 0.97 \\
$\log{\xi}$ & ${\rm erg~cm}$                     & 2.35  & 2.40  & 2.63  & 2.51 \\
$N_{\rm{H}}^{x\rm abs}$ & $10^{22}$~cm$^{-2}$& 4.12  & 4.63  & 3.97  & 1.94 \\
\hline
$f_z$               &                                    & 0.317 & 0.274 & 0.132 & 0.200 \\
$L_{\rm line}$ & $10^{42} {\rm ~ph / s}$           & 11.2  & 9.04  & 3.63  & 2.97  \\
\hline
{\bf calculated values}&&&&&\\
$EM$ & $10^{57} {\rm ~ph / cm^3}$              & 3.46  & 3.23  & 2.69  & 1.45 \\
$n r^2$ & $10^{34}{\rm ~cm^{-1}}$              & 6.16  & 4.18  & 2.48  & 3.00 \\
\hline
\textbf{case 1}&                                         &       &       &       &      \\
$n x$ & $10^{22}{\rm ~ cm^{-2}}$ & 0.45  & 0.62  & 0.86  & 0.39 \\
$f^{\prime} = N_{\rm{H}}^{x\rm abs}/(n x)$ &                   & 9.23  & 7.47  & 4.62  & 4.97 \\
\par
$n$ & $10^{11}{\rm ~ cm^{-3}}$                 & 27.6  & 50.4  & 64.0 & 12.2 \\
\par
$R_p$ & $10^{11}{\rm ~ cm}$                    & 1.4  & 0.9  & 0.6  & 1.5 \\
$R_d\ $ & $10^{11}{\rm ~ cm}$                    & 0.8  & 0.5  & 0.5  & 1.1 \\
$M $ & $10^{-12}~{~M_{\odot}}$                & 1.1  & 0.5  & 0.2  & 0.6 \\
\hline
\textbf{case 2} &                                        &       &       &       &      \\
$n r $ & $ 10^{22}{\rm ~ cm^{-2}}$ & 1.34  & 1.85  & 2.59  & 1.16 \\
$f^{\prime}=N_{\rm{H}}^{x\rm abs}/(n r)$ &                   & 3.08  & 2.50  & 1.53  & 1.67 \\
\par
$n $ & $10^{11}{\rm ~ cm^{-3}}$                 & 0.2  & 0.5  & 0.6  & 0.1 \\
\par
$R_p $ & $10^{11}{\rm ~ cm}$                    & 14.9  & 9.0  & 6.2  & 15.5 \\
$R_d $ & $10^{11}{\rm ~ cm}$                    & 0.5 & 0.3  & 0.5  & 0.9 \\
$M $ & $10^{-12}{~M_{\odot}}$                & 22.5  & 8.9  & 3.1  & 10.9 \\
\hline
\end{tabular}
\end{table}