\begin{table}%t1
%\centering
\par
\caption{\label{t2}Apsidal motion and LITE elements of AO~Mon.}
\begin{tabular}{ccc}
\hline\hline\noalign{\smallskip}
Parameter & Unit & Value \\
\noalign{\smallskip}\hline\noalign{\smallskip}
$T_0$ & HJD  & 2~440~588.3277 (8) \\
$P_{\rm s}$ & days & 1.88476297 (7)     \\
$P_{\rm a}$ & days & 1.88505049 (7)     \\
$e$   &  --  & 0.0177 (6)       \\
$\dot{\omega}$ & deg $\:\rm{cycle^{-1}}$ & 0.0549 (8) \\
$\dot{\omega}$ & deg $\:\rm{yr^{-1}}$    & 10.6 (0.2)  \\
$\omega_0$     & deg      &  238.9 (0.7) \\
$U$            & years    &   33.8 (0.5) \\
\noalign{\smallskip}\hline
\noalign{\smallskip}
$A$   & days    & 0.0061 (2)   \\
$P_3$ & years   & 3.56 (3)    \\
$e_3$ & --      & 0.0  (0.05)   \\  
$\omega_3$      & deg &  54 (1)  \\
$T_3$           & JD  &  2~452~820 (5) \\
$f(m)$          & \ms &  0.093 \\
$M_{3, \min}$    & \ms &  2.5   \\
$K$             & \ks &  8.8   \\ 
\hline
\end{tabular}
\end{table}