\begin{table}%t1
\caption{\label{table:1}The roots $R_{1}$, $R_{2}$ of the function~$\Delta r(R)$.}
\small%\centerline
 {
\begin{tabular}{lccccccc}
\hline \hline
Source~~~~~&\multicolumn{4}{c}{Set~I}&\multicolumn{3}{c}{Set~II}\\
&$\chi^2_\L/{\rm d.o.f.}$&$\chi^2_\U/{\rm d.o.f.}$&$R_1(\Delta r = 0)^\dagger$&$R_{2}(\Delta r = 0)$
&{$\chi^{2}/{\rm d.o.f.}$}&$R_{1}(\Delta r = 0)$
&$R_{2}(\Delta r = 0)$\\
\hline 
4U~1608-52 &17/38&15/9& $1.48\pm0.01$ & -- &{13/8}$^*$& \grayarrea{$1.51\pm0.01$} & $1.25\pm0.01$  \\
4U~1636-53 &1.7/11&40/23& $1.49\pm0.01$ & -- &{18/15}$^*$& \grayarrea{$1.49\pm0.01$} & $1.25\pm0.01$  \\
4U~0614+09 &59/15&16/4& $1.45\pm0.01$ & -- &{3.8/10}$^*$& \grayarrea{$1.48\pm0.01$} & --  \\
4U~1728-34 &40/36&6.3/7& $1.48\pm0.01$ & -- &{21/23}$^*$&\grayarrea{$1.50\pm0.01$} & --  \\
4U~1820-30 &23/35&15/7& $1.46\pm0.01$ & $1.31\pm0.02$ &32/15& -- & $1.34\pm0.02$  \\
4U~1735-44 &2.6/4&2.5/2& $1.53\pm0.02$ & $1.34\pm0.01$ &4.1/8& -- & $1.33\pm0.01$\\
\hline
\end{tabular}}
\medskip
$^\dagger$ The errors shown correspond to a unit variation of~$\chi^{2}$; for asymmetric errors, we use the larger one;
$^*$ corresponds to the linear part of curve between $R =1.4{-}1.6$.
\end{table}