\begin{table}%t1
\par
\caption{\label{t1}Means and standard deviations (results in mas).}
%\centering
\par
\begin{tabular}{lllll}
\hline\hline
 & $\mu $ & $\sigma $ & $E[]$ & $\sigma $ \\ \hline
$\Delta \alpha \cos \delta $ & 11$'$41 & 83$'$46 & 11$'$43 & 88$'$15 \\ 
$\Delta \delta $ & $-46'$03 & 89$'$16 & $-45'$75 & 9$6'$60 \\ \hline
\end{tabular}
\end{table}