\begin{table}%T1
\par
%\centering
\par
\caption{General information about the observations.
                In the table, (date) is that of observation night,
                $(T)$ is the total time length of the observation in
                minutes, $(N)$ is the number of images, $(S)$ is
                the mean number of reference stars, $(C)$ is the
                dimension of the CCD in pixel, $(P)$ is the size
                of the pixel in $\mu $m and $(s)$ is the plate scale
                in arcsecond. For the CCD used in 2000 the pixel
                is  binned from the original $\rm 9~\mu m\times 9~\mu m$
                size.}\label{t1}
\par
\begin{tabular}{ccccccc}\hline\hline
\par
Date & $T$ & $N$ & $S$ & $C$ & $P$ & $s$\\\hline
2002-08-08  &  46  &  23  & 50  &  1024 $\times$ 1024 & 22  $\times$  22 & 0.30 \\
2002-08-10  &  96  &  22  & 40  &  1024 $\times$ 1024 & 22  $\times$  22 & 0.30 \\\hline
2001-08-21  & 111  &  15  & 20  &  1024 $\times$ 1024 & 22  $\times$  22 & 0.30 \\
2000-10-12  &  60  &   4  & 12  &  1536 $\times$ 1024 & 18  $\times$  18 & 0.25 \\\hline
\end{tabular}
\end{table}