\begin{table}%t1
%%\centering
\par
\caption{\label{Tab:darwin_spec}Instrumental parameters considered in this study for \darwin/TPF.}
%\centerline
 {\small\begin{tabular}{l c}
\hline     \hline
Instrumental parameters & Emma X-Array design\\
      \hline
      Max. baselines [m] & $400 \times 67$ \\
      Telescope diameter [m] & 2.0 \\
      Field of regard & 46$^\circ$ to 83$^\circ$  \\
         Optics temperature [K] & 40 \\
      Detector temperature [K] & 8 \\
         Quantum efficiency & 70\% \\
      Instrument throughput$^a$ & 10\% \\
      Science waveband [$\mu$m] & 6.0--20.0 \\
      Modal filtering [$\mu$m]$^b$ & 6.0--11.5/11.5--20.0\\
      Spectral resolution & 60 \\
      Instrumental stability$^c$ & \\
      \hspace{0.4cm}- rms OPD error [nm] & 1.5 \\
      \hspace{0.4cm}- rms amplitude error & 0.05\%\\
\hline
     \end{tabular}}
\medskip
 $^a$ Excluding ideal beam combiner losses and coupling efficiency;
 $^b$ see Sect.~\ref{sec:coupling}; $^c$ see Sect.~\ref{sec:instab}. 
 \end{table}