\begin{table}%t2
\caption{\label{tab2}The data subsets.}
%\centering
\begin{tabular}{ccc}
\hline\hline\noalign{\smallskip}
Data   & Range (JD) \\
\hline 
Setset 1  & 2~454~775.8--2~454~807.8 \\
Setset 2  & 2~454~825.7--2~454~860.7 \\
Setset 3  & 2~454~861.7--2~454~884.7 \\
Setset 4  & 2~454~847.6--2~454~884.7 \\
\hline
\end{tabular}
\end{table}