\begin{table}%t1
\caption{\label{Table_obs}Number of observations in each spectral window within each time block.}
%\centering
\par
\begin{tabular}{cccc}
\hline\hline\noalign{\smallskip}
Spectral window & P1 & P2 & P3 \\
\hline
Lyman-$\alpha$ & 25 & 12 & 13 \\
Lyman-$\beta$ & 40 & 20 & 20 \\
Lyman-$\gamma$ and Lyman-$\delta$ & 39 & 20 & 20 \\
Lyman-5 to continuum & 10 & 10 & 10 \\
\hline
\multicolumn{4}{c}{\small P1 -- 16:03:15 UT to 20:40:59 UT} \\
\multicolumn{4}{c}{\small P2 -- 20:46:27 UT to 23:01:26 UT} \\
\multicolumn{4}{c}{\small P3 -- 23:04:54 UT to 01:21:51 UT} \\
\hline
\end{tabular}
\end{table}