\begin{table}%t2
\caption{Comparison with \citet{cu:74} and other proper motion results from 
the literature. The table only contains Cudworth objects for which a 
meaningful comparison with our results is possible. Results from Cudworth 
have been processed from FK4 to FK5.
The first part of the table contains objects that had 
a significant ($\ge$3$\sigma$) proper motion modulus in Cudworth's 
catalogue, the second part 
of the table contains objects that had proper motion modulus $< $$3\sigma$ in 
Cudworth's for which we found significant PM, the bottom part lists
objects for which we found other PM data in the literature. 
Objects for which our results provide in an improvement in accuracy of the PM 
modulus with respect to the results by Cudworth or other references are 
typeset in bold. The comparison is also illustrated in Fig.~\ref{f:cud_comp}.}
%\label{tab:cud}
\par
%\centerline
{
\begin{tabular}{l|cc|ccc|cc}
\hline\hline
  &\multicolumn{2}{c|}{Cudworth in FK5} & \multicolumn{3}{c|}{this compilation} & \multicolumn{2}{c}{literature}\\  
  PN name &  $\mu_{\alpha}$ & $\mu_{\delta}$  & $\mu_{\alpha}$ &  $\mu_{\delta}$  & Source & $\mu_{\alpha}$ &  $\mu_{\delta}$\\  
\hline
%A~24 & $-$6.5~$\pm$~2.0 & 4.4~$\pm$~3.9 & $-$6.5~$\pm$~2.0 & 4.4~$\pm$~3.9 & 22.9~$\pm$~10.0 & $-$35.5~$\pm$~22.0 & - & - \\
{\bfseries{NGC~246}} & $-$17.9~$\pm$~1.0 & $-$15.4~$\pm$~4.2 & $-$22.0~$\pm$~1.5 & $-$8.3~$\pm$~1.2 & \ucac\ & - & - \\
A~33 & $-$14.8~$\pm$~3.9 & 10.0~$\pm$~2.4 & $-$25.3~$\pm$~4.0 & 1.7~$\pm$~8.0 & \gsc\ & - & - \\
{\bfseries{A~36}} & 20.5~$\pm$~3.7 & 1.0~$\pm$~3.6 & 12.0~$\pm$~1.4 & 3.5~$\pm$~1.3 & \ucac\ & - & - \\
NGC~6309 & 8.5~$\pm$~3.7 & 14.1~$\pm$~4.1 & $-$25.6~$\pm$~28.0 & 63.7~$\pm$~24.0  & \gsc\ & - & - \\
NGC~6629 & $-$1.2~$\pm$~1.2 & 6.5~$\pm$~1.0 & $-$2.8~$\pm$~1.8 & 1.3~$\pm$~1.8 & \ucac\ & - & -\\
NGC~6751 & 1.4~$\pm$~1.2 & $-$5.4~$\pm$~1.0 & $-$9.2~$\pm$~3.0 & $-$5.9~$\pm$~3.1 & \ucac\ & - & - \\
{\bfseries{M~1-67}} & $-$0.4~$\pm$~1.0 & $-$10.6~$\pm$~2.5 & $-$3.1~$\pm$~1.0 & $-$6.2~$\pm$~1.4 & \ucac\ & - & - \\
{\bfseries{BD+30~3639}} & $-$0.5~$\pm$~1.2 & $-$22.4~$\pm$~4.0  & $-$3.0~$\pm$~0.6 & $-$8.7~$\pm$~0.6 & \ucac\ & - & - \\
NGC~6833 & 15.6~$\pm$~2.3 & $-$1.0~$\pm$~3.3 & $-$7.6~$\pm$~2.0 & $-$5.7~$\pm$~2.0 & \gsc\ & - & - \\
NGC~6891 & 2.1~$\pm$~1.0 & $-$9.6~$\pm$~3.1 & 3.8~$\pm$~1.5 & $-$3.4~$\pm$~3.2 & \ucac\ & - & - \\
IC~5117 & 21.4~$\pm$~3.0 & $-$4.8~$\pm$~4.3 & 13.9~$\pm$~16.0 & $-$3.0~$\pm$~10.0 & \gsc\ & - & - \\
{\bfseries{NGC~7293}} & 42.0~$\pm$~2.8 & $-$5.0~$\pm$~1.9 & 37.3~$\pm$~2.5 & $-$3.9~$\pm$~1.8 & \ucac\ & 30~$\pm$~5 & $-$1~$\pm$~0$^2$\\
\hline
{\bfseries{NGC~1514}} & $-$2.9~$\pm$~1.7 & $-$4.3~$\pm$~3.6 & $-$5.9~$\pm$~0.6 & 2.7~$\pm$~0.8 & \ucac\ & - & -\\
{\bfseries{IC~4593}} & $-$4.7~$\pm$~2.1 & 1.1~$\pm$~3.4 & $-$6.5~$\pm$~1.2 & 2.8~$\pm$~1.2 & \ucac\ & $-$11.4~$\pm$~1.7 & 3.1~$\pm$~1.6$^1$\\
{\bfseries{NGC~6210}} & $-$0.4~$\pm$~2.5 & $-$6.9~$\pm$~7.5 & 1.3~$\pm$~1.0 & $-$13.2~$\pm$~0.8 & \ucac\ & $-$9.6~$\pm$~3.8 & $-$16.0~$\pm$~3.8$^3$\\
{\bfseries{NGC~6644}} & $-$15.5~$\pm$~5.4 & $-$7.9~$\pm$~6.1 & $-$12.9~$\pm$~1.7 & $-$8.8~$\pm$~1.6 & \ucac\ & - & -\\
IC~4732 & 4.0~$\pm$~1.0 & 3.7~$\pm$~4.2 & $-$14.3~$\pm$~4.0 & 17.4~$\pm$~4.0 & \gsc\ &-  & -\\
\hline 
EGB~4 & - &  - & $-$3.1~$\pm$~4.0 & $-$33.8~$\pm$~4.0 & \gsc\ & 3.9~$\pm$~4.0 & $-$25.1~$\pm$~ 1.8$^4$\\
{\bfseries{He~2-131}} & - &  - & $-$3.0~$\pm$~1.0 & $-$2.6~$\pm$~1.6 & \ucac\ & $-$7.9~$\pm$~2.7 & $-$2.0~$\pm$~2.4$^3$\\
{\bfseries{NGC~3132}} & - &  - & $-$8.1~$\pm$~1.0 & 1.2~$\pm$~1.2 & \ucac\ & $-$9.0~$\pm$~2.4 & 5.7~$\pm$~2.1$^1$\\
NGC~7094 & - &  - & 4.4~$\pm$~1.5 & $-$10.0~$\pm$~1.5 & \ucac\ & 3.5~$\pm$~0.8 & $-$10.9~$\pm$~0.8$^5$ \\
{\bfseries{Sh~2-68}} & - &  - & $-$22.6~$\pm$~4.0 & $-$52.8~$\pm$~4.0 & \gsc\ & $-$19.9~$\pm$~5.6 & $-$49.3~$\pm$~5.5$^6$\\
\hline 
\end{tabular}}
\medskip
\par
$^1$~\citet{hoeg:98}, $^2$~\citet{har:80}, $^3$~\citet{roe:98}, 
$^4$~\citet{gre:01}, $^5$~\citet{duc:06}, $^6$~\citet{ke:02}.
\label{t:cud_comp}
\end{table}