\begin{table}%t2
\caption{Number of quasars cross-identified between the recent catalog 
of V\'{e}ron Cetty \& V\'{e}ron (\cite{Vero03}) and two~categories of catalogs 
used in the construction of the ICRF: the combination of the defining, candidate and other 
sources of Table~\ref{table 1}, with 608~sources, and its extension, the ICRF-Ext.2~catalog containing 717~sources. Two~different angular thresholds have been chosen for the cross-identification: 2$''$ and~4$''$. The~rms concern the differences in the positions, in arcsecond, for the cross-identified sources. }\label{table 2}
%\centering
\small
\begin{tabular}{lrrrr}
\hline\hline
Catalog & Threshold  &   ICRF             &  ICRF-Ext.2  \\
VV2003    &  ($''$)       &  (3 categories)    &              \\
\hline 
Quasars   & 4  & 361/608    & 403/717         \\ 
          &  &   (59.4\%) &    (56.2\%)         \\
 rms ($''$) $\alpha$/$\delta$        &  & 0.84/0.73  &   0.84/0.72     \\
BL LAC  & 4  &  63/608    & 66/717  	     \\ 
	&  &   (10.4\%) &  (9.2\%)        \\
 rms ($''$) $\alpha$/$\delta$         &  & 0.76/0.55  &   0.77/0.55     \\
Active galaxies  & 4  &  50/608    & 69/717          \\ 
	 &  &   (8.2\%)  &  (9.6\%)        \\
 rms ($''$) $\alpha$/$\delta$ &  &  0.90/0.64 & 0.93/0.82       \\
All objects  & 4  &  474/608    & 538/717          \\ 
              rms ($''$) $\alpha$/$\delta$&  &   (77.9\%)  &  (75.0\%)        \\
\hline
Quasars  & 2  & 349/608    & 390/717         \\ 
	 &  &   (57.4\%)  &    (5.4\%)       \\
 rms ($''$) $\alpha$/$\delta$         &  & 0.77/0.67  &   0.77/0.65     \\
BL LAC   & 2  &  63/608    & 66/717  	     \\ 
         &  &   (10.4\%) &  (9.2\%)        \\
 rms ($''$) $\alpha$/$\delta$           &  & 0.76/0.55  &   0.77/0.55     \\
Active galaxies   & 2  &  48/608    & 64/717          \\ 
               &  &   (7.8\%)  &  (8.9\%)        \\
 rms ($''$) $\alpha$/$\delta$  &  &  0.78/0.64 & 0.75/0.67       \\
All objects  & 2  &  460/608    & 520/717          \\ 
 &  &   (75.7\%)  &  (72.5\%)        \\
 rms ($''$) $\alpha$/$\delta$    &  &     &    \\   	      	
\hline
\end{tabular}
\end{table}