\begin{table}%t1
%\centering
\par
\caption{\label{table:1}Evolution of the quality of the LLR residuals for each station.}  \begin{tabular}{c c r r} % centered columns (4 columns)
\hline\hline
Observatory & Period of observation & rms & $N$ \\ % table heading
&&(cm) &\\
\hline 
McDonald & 1969--1986 & 46 & 3522 \\ & 1987--2006  & 9.2 & 3080 \\ % inserting body of the table
Haleakala & 1984--1990  & 11.1 & 481 \\
Grasse & 1984--1986 & 24.6 & 1130 \\ & 1987--2005  &  5.1 & 8142 \\
\hline
\end{tabular}
\end{table}