\begin{table}%T1 
%\centering
 \small 
\caption{Description of the data-set used for this work.}  
\label{obs}     
\begin{tabular}{cccc} 
\hline\hline    
filter & Exp-time & seeing & airmass\\ 
\hline      
%------------------------------------------------------------------------------------------ 
%& & & \\
%\hline
\multicolumn{4}{c}{ {Bulge --- Baade window} } \\
\hline    
%& & & \\
\multicolumn{4}{c}{calibration data, June 6, 2003}\\
%& & & \\
 $U$  &   3 $\times$ 350 s;    &  ${\sim} 1\farcs3$    & 1.18--1.23 \\
 $V$  &  30 $\times$ 60 s;     &  $0\farcs7$--$1\farcs6$ & 1.00--1.13 \\
%& & & \\
%------------------------------------------------------------------------------------------
%& & & \\
\hline
\multicolumn{4}{c}{ {NGC~2477} } \\
\hline    
%& & & \\
\multicolumn{4}{c}{test data, January 20, 1999}\\
%& & & \\
 $I_{\#853}$  &  6 $\times$ 900 s;     &  $0\farcs9$--$1\farcs1$ & 1.05--1.33 \\
%& & & \\
%------------------------------------------------------------------------------------------
\hline          
\multicolumn{4}{c}{ {NGC~6121 (M~4)} }\\
\hline          
%& & & \\
\multicolumn{4}{c}{Epoch I: August 17-18, 1999}\\
%& & & \\
 $B$  & 3 $\times$ 180 s;                     & ${\sim} 1\farcs3$ & 1.04 \\
 $V$  & 3 $\times$ 180 s;                     & ${\sim} 1\farcs5$ & 1.20 \\
%& & & \\[-2mm]
\multicolumn{4}{c}{Epoch II: June 21, 2002}\\
%& & & \\[-2mm]
 $B$  & 3 $\times$ 5 s;    1 $\times$ 100 s;    & ${\sim} 1\farcs4$ & 1.20 \\
 $V$  & 3 $\times$ 10 s;   6 $\times$ 90 s;     & ${\sim} 1\farcs1$ & 1.10 \\
%& & & \\
%------------------------------------------------------------------------------------------
\hline          
\multicolumn{4}{c}{ {NGC~6397}}\\
\hline          
%& & & \\
\multicolumn{4}{c}{Epoch I: May 14, 1999}\\
%& & & \\
 $B$  & 1 $\times$ 20 s;    2 $\times$ 240 s;    & ${\sim} 1\farcs1$ & 1.10 \\
 $V$  & 1 $\times$ 20 s;    2 $\times$ 240 s;    & ${\sim} 1\farcs2$ & 1.08 \\
 $I$  & 1 $\times$ 20 s;    2 $\times$ 240 s;    & ${\sim} 1\farcs0$ & 1.09 \\
%& & & \\[-2mm]		                    
\multicolumn{4}{c}{Epoch II: June 18, 2002}\\
%& & & \\[-2mm]
 $U$  & 3 $\times$ 35 s;    3 $\times$ 240 s;    & ${\sim} 1\farcs4$ & 1.08 \\
 $B$  & 3 $\times$ 5 s;     3 $\times$ 90 s;     & ${\sim} 1\farcs2$ & 1.10 \\
 $V$  & 3 $\times$ 3 s;     8 $\times$ 70 s;     & ${\sim} 1\farcs3$ & 1.11 \\
 $I$  & 1 $\times$ 3 s;     2 $\times$ 3 s;      & ${\sim} 1\farcs1$ & 1.21 \\
      & 1 $\times$ 49 s;    3 $\times$ 50 s;     & ${\sim} 1\farcs1$ & 1.21 \\
\hline
\end{tabular} 
\end{table}