\begin{table}%t1
\caption{Summary of the observations.}\label{tab1}
%\centering
\par
\begin{tabular}{llccc}
\hline
\hline
Telescope & Filter & exposure & seeing ($''$) & airmass  \\
\hline
$CFHT$ & $R$ & 250 s & 0.93 & 1.140\\
$CFHT$ & $I$ & 240 s & 0.73 & 1.143\\
$CFHT$ & CN & 560 s & 0.61 & 1.150\\
$CFHT$ & TiO & 560 s & 0.71 & 1.151\\
$TNG$ & $R$ & $2\times 450$ s & 1.29 & 1.26\\
$TNG$ & $I$ & $2\times 450$ s & 1.10 & 1.31\\
\hline
\end{tabular}
\end{table}