\begin{table}%t2
\caption{\label{tab2}SSO 2.3 m spectrograph configurations (see text).}
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\par
\begin{tabular}{rccc}
\hline\hline
 night 1994 & config.& \multicolumn{2}{c}{wavelength ranges}    \\
            & number &    blue channel   &   red channel        \\
\hline
      December 25 &  1 & 3500 \AA--4500 \AA & 6470 \AA--7550 \AA  \\
      December 26 &  2 & 4475 \AA--5550 \AA & 7500 \AA--8570 \AA  \\
      December 27 &  3 & 5510 \AA--6550 \AA & 8530 \AA--9650 \AA  \\
      December 28 &  1 & 3500 \AA--4500 \AA & 6470 \AA--7550 \AA  \\
      December 29 &  2 & 4475 \AA--5550 \AA & 7500 \AA--8570 \AA  \\
      December 30 &  3 & 5510 \AA--6550 \AA & 8530 \AA--9650 \AA  \\
      December 31 &  1 & 3500 \AA--4500 \AA & 6470 \AA--7550 \AA  \\
\hline
\end{tabular}
\end{table}