\begin{table}%t1
\caption{\label{obs}Summary of the test field observations.}
\small%\centerline
{
\begin{tabular}{@{}l@{}ccccc@{}}
\hline
\hline
         & No. of nights &  Camera         & Spectr.& $T$     &   Seeing,   \\ 
Date     & /images       & /unit  & band   & s    &   arcsec   \\ 
\hline
Dec. 2000 & 4/40     & FORS1/UT1   &  $B$   & 620 & 0.49--0.78  \\
Dec. 2002 & 4/25     & FORS1/UT1   &  $B$   & 620 & 0.46--0.83  \\
Dec. 2006 & 1/5      & FORS1/UT2   &  $B$   & 560  & 0.55--0.65 \\
Nov. 2006 & 1/27     & FORS2/UT1   &  $R$   & 70  & 0.48--0.62 \\
Dec. 2006 & 1/37     & FORS2/UT1   &  $R$   & 70  & 0.34--0.73 \\
Jan. 2007 & 1/27     & FORS2/UT1   &  $R$   & 70  & 0.56--0.89 \\
Feb. 2007 & 1/27     & FORS2/UT1   &  $R$   & 70  & 0.45--0.63 \\
Mar. 2007 & 1/27     & FORS2/UT1   &  $R$   & 70  & 0.57--0.76 \\
\hline                
\multicolumn{5}{l}{Standard limits for seeing*:} & 0.47--0.78 \\
\hline
\end{tabular}}
\smallskip 
 * Images with seeing out of these limits are affected by large random and
systematic errors in positions (Sect.~6). 
\end{table}