\begin{table}%t7
\caption {\label{table:7}Numerical amplitudes of the fitted terms (i.e constant term, secular term, 18.6-yr nutation term) for the VLBI series.} % title of Table
%\centering
 % used for centering table
\begin{tabular}{c r r} % centered columns (4 columns)
\hline\hline % inserts double horizontal lines
Terms & $DX$ (mas)  & $DY$ (mas)  \\ % table heading
\hline % inserts single horizontal line
sin (18.6-yr) & $ -0.007\pm 0.003$  & $ 0.016\pm 0.003$ \\
cos (18.6-yr) & $ 0.057\pm 0.004$  & $ -0.066\pm 0.004$ \\
secular term (mas/cy) & $0.164 \pm 0.060$ & $-0.155 \pm 0.060$ \\
constant term & $0.045 \pm 0.002$ & $-0.102 \pm 0.002$ \\
\hline %inserts single line
\end{tabular}
\end{table}