\begin{table}%t2
%\centering
\par
 \caption{\label{tab:db07}Results for the periods obtained by \citet{demoortel2007}.}
  \begin{tabular}{lccc}
  \hline \hline
  Slit & $P_i$ & $P_{ii}$ & $P_{iii}$ \\ \hline
  Upper 1 & 1806 & 577 & 301 \\
  Upper 2 & 1620 & 606 & 295 \\
  Central & 2484 & 672 & 346 \\
  Lower & 1038 & 660 & 250 \\
\hline
 \end{tabular}\vspace{-3mm}
\end{table}