\begin{table}%t8
\caption{Confidence intervals for different redshifts.  }\label{table11}
%\centerline
 {\small \begin{tabular}{cccc}
\hline
\hline
 $z$   & $\Delta z$& Reported interval  & Confidence interval  \\ 
 $(1)$ & $(2)$ &$(3)$ &$(4)$ \\ \hline
  $  0.238$&$  1.21$&$(-0.89,3.31)$&$(-0.96,0.50)$ \\ 
 $  0.312$&$  1.06$&$(-4.87,3.66)$&$(-0.96,0.50)$ \\ 
 $  0.395$&$  0.90$&$(0.07,6.38)$&$(-0.96,0.50)$ \\ 
 $  0.524$&$  0.65$&$(-4.00,-1.90)$&$(-0.96,0.50)$ \\ 
 $  0.525$&$  0.64$&$(-3.41,3.93)$&$(-0.96,0.50)$ \\
 $  1.776$&$  0.58$&$( -3.493,-1.69)$&$(-1.44,0.15)$ \\ 
 $  1.944$&$  0.38$&$(2.85,3.74)$&$(-1.35,0.63)$ \\ 
 $  2.039$&$  0.47$&$(2.43,7.96)$&$(-1.72,0.68)$ \\ 
 $  2.347$&$  0.41$&$(-4.36,-0.72)$&$(-1.70,0.37)$ \\
  \hline
\end{tabular}}
\medskip
 Notes. Columns: $(1)$ redshift; $(2)$ length of the redshift  interval for which the confidence interval is calculated;  $(3)$ single value reported by \citet{Tzana07}    in units of $10^{-5}$; $(4)$ calculated confidence interval   from a group of data reported by  \citet{Murphy03b} 
  in units of~$10^{-5}$. 
\end{table}