\begin{table}%t1
 \caption{GRB samples of known durations ($T_{90}$),
redshifts~($z$) and/or peak energies ($E_{\rm p}$).
\label{tab1}}
%\centerline
 {\begin{tabular}{c c clr}
\hline\hline
Sample & No.&Class & Parameters &Ref.\\
\hline\\[-3mm]
$\rm s1^{\dag}$& 75&LGRBs&$T_{90}$; $z$&1; 1; --\\
$\rm s2^{\dag}$& 20&SGRBs&$T_{90}$; $z$&1; 1; -- \\
$\rm s3^{\dag}$& 44&LGRBs&$T_{90}$; $z$; $E_{\rm p}$&1; 1; 4 \\
$\rm s4^{\dag}$& 11&SGRBs&$T_{90}$; $z$; $E_{\rm p}$&1; 1; 4 \\
$\rm s5^{\ddag}$& 48&LGRBs&$T_{90}$; $z$&2, 3; 5; --\\
$\rm s6^{\sharp}$& 18&LGRBs&$T_{90}$; $z$&2, 3; 5;--\\
\hline
\end{tabular}}
\par
\smallskip
Note: the references are given in order for $T_{90}$, $z$
and $E_{\rm p}$. Data sets: $^{\dag}$ Swift; $^{\ddag}$ pre-Swift;
$^{\sharp}$ BATSE. Of the 20~SGRBs, \object{GRB 050709}, is
adopted from HETE-2. 
{Reference}: 1. Swift public webpage; 2. Ghirlanda,
Ghisellini \& Lazzati (2004); 3. \textit{GRBlog} website; 4. Butler 
et~al. (\cite{Butler07}); 5. Friedman \& Bloom (2005).
\end{table}