\begin{table}%t3
%\centering
\par
\caption{\label{comb}First 20 frequencies identified in the amplitude spectrum.}
\begin{tabular}{r rr c}
\hline \hline
\multicolumn{1}{c}{Term} & \multicolumn{1}{c}{Frequency}&
\multicolumn{1}{c}{Ampl.} & Possible combination  \\
\multicolumn{1}{c}{}& \multicolumn{1}{c}{[d$^{-1}$]} & 
\multicolumn{1}{c}{[mmag]} &terms \\
\hline
 $f_1$    &  6.92528 & 15.4539 & $f_{29}=2f_1$, $f_{215}=3f_1$ \\
 $f_2$    & 11.21669 &  6.7220 & $f_{112}=f_1+f_2$, $f_{123}=f_2-f_1$\\
          &          &         &  $f_{414}=2f_2$ \\
 $f_3$    & 11.25807 &  4.0143 & $f_{159}=f_1+f_3$, $f_{806}=f_3-f_1$ \\
 $f_4$    & 12.84846 &  3.3603 & $f_{129}=f_1+f_4$, $f_{791}=f_4-f_1$ \\
 $f_5$    & 12.23831 &  3.3271 & $f_{217}=f_1+f_5$, $f_{895}=f_5-f_1$ \\
 $f_6$    & 14.44689 &  3.1767 & $f_{118}=f_1+f_6$\\
 $f_7$    & 13.27347 &  2.6672 & $f_{356}=f_1+f_7$\\
 $f_8$    & 13.35865 &  2.3077 & $f_{149}=f_1+f_8$, $f_{736}=f_8-f_1$ \\
 $f_9$    & 11.75102 &  1.4372 & \\
 $f_{10}$ &  5.26653 &  1.1277 & $f_{64}=f_1+f_{10}$\\
 $f_{11}$ & 14.46126 &  1.0604 & \\
 $f_{12}$ & 14.43209 &  0.9731 & \\
 $f_{13}$ &  9.95254 &  0.9385 & $f_{781}=f_{13}-f_1$\\
 $f_{14}$ & 11.98380 &  0.8268 & $f_{619}=f_1+f_{14}$\\
 $f_{15}$ &  6.55624 &  0.8259 & $f_{141}=f_1+f_{15}$\\
 $f_{16}$ &  7.40446 &  0.8099 &  \\
 $f_{17}$ & 13.56880 &  0.7768 & $f_{497}=f_{17}-f_1$\\
 $f_{18}$ & 10.26062 &  0.7332 & $f_{309}=f_1+f_{18}$\\
 $f_{19}$ &  5.78177 &  0.7046 &  \\
 $f_{20}$ &  6.62914 &  0.6435 & $f_{494}=f_1+f_{20}$\\
\hline
\end{tabular}
\end{table}