\begin{table}%t1
\caption{\label{tab:stand}Atmospheric extinction and photometric calibration \mbox{coefficients}.} 
%\centerline
 {\begin{tabular}{l l l l l l} 
\hline\hline 
 Filter   & $\kappa$ &  $c^{a}$  &   $ZP^{a}$  &   $ZP^{b}$  &   $ZP^{c}$ \\
\hline 
$V$  &  0.187  & $-0.108$  & 20.899~$\pm$~0.024  & 20.874  &  20.954 \\ 
$R$  &  0.135  & $-0.110$  & 21.208~$\pm$~0.030  & 21.202  &  21.220 \\
$I$  &  0.072  & $-0.147$  & 20.629~$\pm$~0.020  & 20.577  &  20.608 \\
\hline 
\end{tabular}}
\par
\smallskip	                
$^{{a}}$   From SA~98 standard area observed on December 23, 2006. 
$^{{b}}$   From SA~94-242 observed on January 17, 2007. 
$^{{c}}$   From SA~96-36 observed on January 18, 2007. 
\end{table}