\begin{table}%t4
\par
\caption{\label{Tab4}Summary of the diagnostic parameters.}
\begin{tabular}{lcccc}
\hline \hline
Source & $\alpha_{\rm ox}$ & $\alpha_{\rm ro}$ & $\alpha_{\rm rx}$  & log~($R_{\rm X}$) \\
\hline
IGR~J18249--3243$^{a}$  & 1.15 & 0.75 & 0.86 & --1.82 \\
IGR~J19443+2117   &  $>$1.38 & $<$0.26 & 0.63 & --3.74 \\
IGR~J22292+6647 & $>$1.63  & $<$0.32   & 0.75 &  --2.74 \\
\hline
\end{tabular}
\par
\begin{flushleft}
$^{a}$ For this source $\alpha_{\rm ox}$ and $\alpha_{\rm ro}$ have been estimated 
by extrapolating the {\it UVW2} flux to 2500 $\mbox{\AA}$ 
and using an average UV slope of $\alpha_{\rm uv} =0.4$
 (Vanden Berk et~al. \cite{VandenBerk2001}).
\end{flushleft}
\end{table}