\begin{table}%t1
\caption{\label{tab:observations}Summary of observations of the four sets of targets.}
%\centerline
 {\small \begin{tabular}{llclc}
\hline\hline\noalign{\smallskip}
Date & MJD$^{a}$ & $\Delta$t$^{b}$ & Targets & Integration time\\
\hline
&&&&\\
20/06/2008 & 54~637.190 & --             & Faint 1 & $3 \times 895$~s\\
           & 54~637.230 & --             & Faint 2 & $3 \times 895$~s\\
29/06/2008 & 54~646.185 & --             & Bright  & $2 \times 600$~s\\
           & 54~646.224 & --             & Faint 3 & $3 \times 895$~s\\
%\hline
18/07/2008 & 54~665.036 & 18.85           & Bright  & $2\times600$~s\\
           & 54~665.065 & 18.84           & Faint 3 & $3 \times 895$~s\\
           & 54~665.104 & 27.87           & Faint 2 & $3 \times 895$~s\\
           & 54~665.144 & 27.95           & Faint 1 & $3 \times 895$~s\\
%\hline
24/07/2008 & 54~671.134 &  6.10           & Bright  & $2 \times 600$~s\\
%\hline
14/08/2008 & 54~692.042 & 20.91           & Bright  & $2 \times 600$~s\\
           & 54~692.073 & 27.01           & Faint 3 & $3\times895$~s\\
17/08/2008 & 54~695.094 & 29.99           & Faint 2 & $3\times 895$~s\\
           & 54~695.133 & 29.99           & Faint 1 & $3 \times 895$~s\\  
%\hline
04/09/2008 & 54~713.011 & 20.97           & Bright  & $2 \times 500$~s\\
\hline 
\end{tabular}}
\medskip
$^{a}$ The modified Julian day (MJD) is given at the midpoint of the sequence of integrations; $^{b}$~the time since the target field was last observed.
\end{table}