\begin{table}%T2
\par
%\centering
\par
\caption{\label{tab:expos} Summary of the usable exposure durations
  obtained for the different  clusters after accounting for the GTI
  filtering, telemetry losses etc. In some observations data from only one camera was available. For operational reasons the PN camera commences exposures somewhat later than the MOS cameras. Losses due to proton flares, telemetry drops etc. are given in Col.~4 as a percentage of the total exposure time.} 
\begin{tabular}{l c c l }\hline\hline 
Cluster ID&MOS &PN &\% lost \\\hline 
RX~J0337.7--2522 & 23~421 & 23~611&60 \\ 
RX~J0505.3--2849&31~851&24~983&35\\ 
RX~J0847.2+3449 & 43~793 & -- &50\\ 
RX~J1120.1+4318 & 18~333 & 16~208&18\\ 
RX~J1325.5--3826 & -- & 48~753&20\\ 
RX~J1334.3+5030 & 40~713 & 34~909&15\\ 
RX~J1354.2--0222 & 9090& 7248&73\\ 
RX~J1701.3+6414 & 9379 & 4382&50\\\hline 
\end{tabular}
\end{table}