\begin{table}%t7
%\centering
\par
\caption {\textrm{The 25$\sigma$ AB limiting magnitudes for PS1, PS4 and LSST.\label{mag_table}}}
     \begin{tabular}{c c c c}
     \hline\hline
     {\bf Filter} & {\bf PS1} & {\bf PS4} & {\bf LSST}\\
     \hline
     {\it g} & 21.5 & 22.2 & 22.7\\
     {\it r} & 20.9 & 21.7 & 22.4\\
     {\it i} & 20.8 & 21.6 & 21.8\\
     {\it z} & 19.8 & 20.6 & 21.2\\
     {\it Y} & 18.4 & 19.1 & 19.9\\
     \hline
     \end{tabular}
\end{table}