\begin{table}%t1
%%\centering
\par
\caption{Photometric offsets.}  
%\centerline
{\begin{tabular}{llcccccccc} 
\hline  \hline
Data&Catalog  & $\Delta U$          &  $\Delta B$       	&  $\Delta V$	    & $\Delta R$	   & $\Delta I$  & \\
\hline
CCD:&         &         	       &  	 	        &  	 	         &	   &	    & \\
    &B93      & ....    	       & $-$0.37	 	        & 0.00	 	         & $-$0.42   & 0.00   &\\
    &RHH92/94 & ....    	       & 0.00	 	        & 0.00	 	         & 0.00	   & ....   &	 \\
    &M98      & ....    	       & ....	 	        & 0.00	 	         & ....	   & 0.00   &	 \\
PE: &         &         	       &  	 	        &  	 	         &	   &	    &  \\
    &SL83     & 0.00    	       &0.00	 	        & 0.00	 	         & ....	   & ....   &	 \\ 
    &SL85+    & 0.00    	       & 0.00	 	        & 0.00	 	         & ....	   & ....   &	\\
PG: &         &         	       &  	 	        &  	 	         &	   &	    &  \\
    &B87      & 0.00 (if $U\leq17.9$)  & 0.00  (if $B\leq18$)   & 0.00	 (if $V\leq16.5$)&	   &	    &  \\
    &         &$-0.27U+4.8$ (if $U>17.9$)&$-0.31B+5.64$ (if $B>18$) &$-0.13V+2.17$ (if $V>16.5$)&$-0.03r_{\rm c}+0.16$&$\ast$  &  \\
\hline  \end{tabular}}
Reference:
RHH92 \citet{reed92};
RHH94 \citet{reed94};
B93   \citet{Battistinib};
M98   \citet{Mochejska};
SL83   \citet{Sharov83};
SL85+ \citet{sh85} and succeeding papers; 
B87   \citet{Battistinia}; ($\ast$) unpublished $I$ photographic magnitudes
      (Federici \& Fusi Pecci, private communication). 
     The indicated offset have been applied to the
     photometries of the different sources to transform them into the
     photometric system of \citet{Barmbya}.
\end{table}