\begin{table}%t1
\caption{\label{tab:parameters}The contour levels used in the core extraction.} 
\small%\centerline
 {
\begin{tabular}{c c c}
\hline\hline      
%&& \\[-8pt]
\# & $A_{\rm V}^{\rm th}$ [$\sigma^{\rm rms}$]$^a$ & $\delta A_{\rm V}$ [$\sigma^{\rm rms}$]$^b$ \\ 
%&& \\[-8pt]
\hline                      
   1 & 7 & 7 \\
   2 & 7 & 3  \\ 
   3 & 3   & 7\\ 
   4 & 3   & 5 \\
   5 & 3   & 3 \\
   6 & 3   & 1$^c$ \\
   7 & 2 & 3 \\
   8 & 2 & 1$^c$ \\ 
   9 & 1 & 3 \\
   10 & 1 & 1$^c$ \\ 
\hline                  
\end{tabular}}
\medskip
$^a$ The detection threshold of the core extraction algorithm;
$^b$~the contour level spacing;
$^c$~contour increment $8 \sigma^{\rm rms}$ when $A_{\rm V}>5$~mag.
\end{table}