\begin{table}%t3
\caption{External photometric errors from the artificial star
\mbox{photometry}.}
%\centering
\par
\begin{tabular}{cccc} 
\hline
\hline
$\Delta V$ & $\hat{\sigma}_{{\rm ext},V}$ & $\hat{\sigma}_{{\rm ext},V-I} $ &
$\hat{\sigma}_{{\rm ext},R-I}$  \\
\hline 
 9.5--10.5 & 0.001  &  0.001 &  0.001 \\
 10.5--11.5 & 0.001  &  0.003 &  0.003 \\
 11.5--12.5 & 0.003  &  0.004 &  0.003 \\
 12.5--13.5 & 0.006  &  0.006 &  0.004 \\
 13.5--14.5 & 0.007  &  0.009 &  0.007 \\
 14.5--15.5 & 0.013  &  0.016 &  0.010 \\
 15.5--16.5 & 0.024  &  0.025 &  0.018 \\
 16.5--17.5 & 0.043  &  0.058 &  0.039 \\
 17.5--18.5 & 0.111  &  0.105 &  0.080 \\
 18.5--19.5 & 0.225  &  0.248 &  0.098  \\
\hline
\end{tabular}
\label{photoerror}
\end{table}