\begin{table}%t1 \caption{\label{tab:mpclass}Numbers of different metal-poor classes among the candidate HES turnoff sample, the sample with follow-up observations from SSO, and the accepted sample after the visual inspection and rejection as described in Sect.~\ref{subsec:measurement}.} %\centerline {\small \begin{tabular}{lcccc} \hline\hline\noalign{\smallskip} Class & HES prism & SSO follow-up & Accepted & Factor \\ \hline mpca & 179 & 36 & 29 & 6.17 \\ unid & 333 & 67 & 59 & 5.64 \\ mpcb & 1666 & 560 & 513 & 3.25 \\ mpcc & 1205 & 19 & 16 & 75.31 \\ \hline Total & 3383 & 682 & 617 & \\ \hline \end{tabular}} \tablefoot{The column labelled ``Factor'' refers to the scaling factor used to construct the MDF described in Sect.~\ref{subsec:measurement}} \end{table}