\begin{table}%t1
\caption{Log of observations for RXS J1131-1231 with {\it HST}.}
\label{tab:obs}
%\centering
\small
\begin{tabular}{cccccccc}
\hline \hline
Date & Instrument & Filter & NExp & Exp(s) & Scale ($''$/pix) & RON (e/pix)& $g$ (e/ADU)\\
\hline
17-11-2003 & NICMOS-NIC2 & $F160W$ & 5 & 640 & 0.0759/0.0754$^\dag$ & 26 & 5.4 \\
17-11-2003 & NICMOS-NIC2 & $F160W$ & 3 & 704 & 0.0759/0.0754$^\dag$ & 26 & 5.4 \\
22-06-2004 & ACS-WFC & $F555W$ & 5 & 396 & 0.050$^\ddag$ &5.3 & 2.0\\
24-06-2004 & ACS-WFC & $F814W$ & 5 & 396 & 0.050$^\ddag$ &5.3 & 2.0\\
\hline
\noalign{\smallskip}
\multicolumn{8}{l}{$^\dag$ NIC2 plate scale along $X$ and $Y$ respectively (see {\tt http://www.stsci.edu/hst/nicmos/performance/platescale}).}\\
\multicolumn{8}{l}{$^\ddag$ The reported ACS scale is obtained after drizzling.}
\end{tabular}
\end{table}