\begin{table}%t2
\par
   %\centering
\par
      \caption{\label{t2}Amplitudes and periods of O--C variations in
      CoRoT-1b system.}
\begin{tabular}{llcc}
            \hline\hline
            \noalign{\smallskip}
            Mass of  the &  Configuration & Amplitude & Period\tablefootmark{1}\\
            perturbing object &  &  in seconds & \\
             \hline
	    1 Earth mass & at $L_4$ point, $20^\circ$  & 60 & $\sim $10\\
                         & libration amplitude      &    & \\
	    1 Earth mass & initially on circular orbit,  & 100 & $\sim $150\\
	                 & 2:1 exterior mmr&    &      \\
	    30 Earth mass & outer planet initially  & 150 & $\sim $15\\
	                  & with $e=0.05$ and & & \\
	                  & $P=2.277218632$~days & & \\
	    30 Earth mass & outer planet initially  & 150 & $\sim $30\\  
	                  & with $e=0.25$ and & & \\
	                  & $P=4.2679123$~days & & \\
             \hline
\end{tabular}
\tablefoot{\tablefoottext{1}{In the units of consecutive transit numbers.}}
\end{table}