\begin{table}%t1
%\centering
\par
\caption{"Standard'' clouds.\label{standard_clouds}}
\begin{tabular}{llllll} 
\hline \hline
\noalign{\smallskip} 
Type & $r$(pc)	 & $n({\rm cm}^{-3})$ & $N({\rm cm}^{-2})$         & $G_0$        &  $F_{\rm X}$ [erg~s$^{-1}$~cm$^{-2}$]  \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
A  &  1    & $10^4 {-} 10^{6.5}$  & $3 \times 10^{22}{-}1 \times 10^{25}$   & $10^2{-}10^5$ & $1.6{-}160$      \\
B  &  10   & $10^3 {-} 10^4$      & $3 \times 10^{22}{-}3 \times 10^{23}$   & $10^1{-}10^4$     & $1.6\times10^{-1}{-}16$ \\
C  &  10   & $10^2 {-} 10^3$      & $3 \times 10^{21}{-}3 \times 10^{22}$   & $10^{0.5}{-}10^3$     & $1.6\times10^{-2}{-}1.6$   \\
\hline
\end{tabular}
\end{table}