\begin{table}%t4
\caption{\label{tab4}Amplitude variations in HL Tau 76 between XCOV13 and~XCOV18.}
%\centering
\par
\begin{tabular}{cccc}
\hline\hline
   Frequency &Amplitude &  Frequency   & Amplitude \\
   \ [$\mu$Hz] &  [mma]   &  [$\mu$Hz]   &  [mma]\\
   XCOV13 & XCOV13   & XCOV18  &  XCOV18  \\
\hline
741.9  & 9.2  &   736.7  &  3.1\\
939.4  & 18.3  &   939.0  &  11.3\\
1072.4  &23.2  &   1071.6  &  3.2\\
1255.5  &8.9  &   1255.7 &  3.7\\
1280.3  &9.1  &   abs  &  abs\\
1521.0  &10.3  &   1516.3  &  10.7\\
1675.0  &14.4  &   1675.6  &  14.6\\
1848.3  &37.3  &   1848.6  &  28.4\\
2023.4  &27.8  &   2023.4  &  24.4\\
2223.3  &6.7  &   abs  &  abs\\
2614.6  &20.1  &   2614.5  &  16.5\\
\hline
\end{tabular}
\end{table}