\begin{table}%t1
	\caption{\label{tab:DC_toler}Some examples of approximation introduced by the double cone geometry.}
	%\centerline
{\begin{tabular}{l c c c c}
	\hline \hline
	&SIMBOL-X & NeXT-HXT & NuSTAR & XMM\\
	\hline
	$f$& 20 m & 12 m & $\sim$10 m & 7.5 m\\
	$R_{0, {\rm max}}$& 324 mm & 225 mm & $\sim$169 mm & 346 mm\\
	$L$& 300 mm & 200 mm & 200 mm & 300 mm\\
	\hline
	$\frac{\displaystyle\Delta\alpha}{\displaystyle\alpha_0}$ & 0.4\% & 0.4 \% & 0.5\% & 1\%\\[1.5mm]%\hspace*{2.5mm}
	$\frac{\displaystyle\Delta A_1}{\displaystyle A_1}$& $-0.18$\% & $-0.20$\% & $-0.25$\% & $-0.5$\%\\[1.5mm]
	$\frac{\displaystyle\Delta V}{\displaystyle V}(\delta =0)$& 1.5\% & 1.7\% & 2\% & 4\% \\
	\hline
	\end{tabular}}
	\smallskip
\par
	Optical parameters after Pareschi~et~al.~(\cite{Pareschi08}); Ogasaka~et~al.~(\cite{Ogasaka}); Koglin~et~al.~(\cite{NuSTAR}); Gondoin~et~al.~(\cite{Gondoin1}).
\end{table}