\begin{table}%t1
\caption{Details of the imaging  observations.  The first column gives
the telescope  and instrument used, Col.~4 gives the  pixel size in
\mbox{arcseconds},  while  the  last  column  gives the  integration  time  in~\mbox{seconds}.}\label{obs}
%\centering
\par
\begin{tabular}{ccccc}
\hline\hline 
Instr.  &  Band & Date & scale&  $t$\\ 
\hline 
VLT-FORS2 &$R$ & 13-05-2002 &0.252 & 15 s \\  
VLT-FORS1 & $R$ & 11-04-2000 & 0.200 &30 s \\  
NTT-SOFI & $J$ &  24-02-1999&0.290 & 300 s \\  
1.54 m-DFOSC& $V$ &14-04-1997& 0.390 & 600 s\\ 
\hline
\end{tabular}
\end{table}