\begin{table}%t1
\caption{\label{tab1}{\em ROSAT} NEP properties of the three QSO~2 candidates.}
%\centering
\par
\begin{tabular}[h]{l l c  c c c c c}
\hline
\hline
Source Name & NEP id \#  & PSPC $F_{0.5{-}2.0~\rm keV} \pm \Delta F$ & $z$ (UH or MMT)  & z (TNG) & $N_{\rm H}$ & $L_{0.5{-}2.0~\rm keV}$  &$ M_{\rm B}$ \\
       &  & 10$^{-13}$ erg cm $^{-2}$ s$^{-1}$      &      &  & cm$^{-2}$  & 10$^{44}$ erg s$^{-1}$ & (from USNO $B$ mag)\\
\hline
RX~J1715.4+6239 & NEP~1239 & 1.39~$\pm$~0.30 & 0.8500 & 0.8500 & $2.62\times 10^{20}$ &4.88  & $-23.5$\\
 RX~J1724.9+6636 & NEP~1640 & 1.03~$\pm$~0.25 & 0.6792 & 0.6758 & $3.84\times 10^{20}$ &2.08 & $-23.2$\\
 RX~J1737.0+6601 & NEP~2131 & 1.36~$\pm$~0.20 & 0.3580 & 0.3585 & $3.76\times 10^{20}$ &0.60  & $-24.1$\\
 \hline 
\end{tabular}
\end{table}