\begin{table}%T1
\caption{Broad-band limiting magnitudes (4-m telescope with  a $4096\times4096$  CCD mosaic having 0.4-arcsec pixels, $S/N= 5$).}\label{tab:1}
%\centerline
{
\begin{tabular}{l c c c}
\hline
\hline
& $B$ & $R$ & $I$ \\
\hline
1 night (127 s)$^1$ & 24.4 & 24.1 & 23.7 \\
1 season (7600 s)$^1$ & 26.6 & 26.3& 25.9 \\
4 	seasons (30~500 s)$^1$ & 27.4 & 27.1 & 26.7 \\		\hline
\end{tabular}}
\par
\medskip
$^1$ Because observations in I can be carried out during moonlit nights, I~have assumed integration times twice as 	long  in $I$.
\end{table}