\begin{table}%t4
%\centering
\par
\caption{Extended spectral transformation equations.}\label{ta:propeqn}
\begin{tabular}{l@{\hspace{15pt}}l}
   \hline\hline
   \noalign{\medskip}
   \Mc{\nu = \nu_0 \left(1 - \frac{V}{c}\right)
         \label{eq:P1}} &
      \Ma{\Dfrac{\nu}{V} = -\frac{\nu_0}{c}
         \label{eq:P2}} \\
   \Mc{V = c \frac{\nu_0 - \nu}{\nu_0}
          \label{eq:P3}} &
      \Ma{\Dfrac{V}{\nu} = -\frac{c}{\nu_0}
          \label{eq:P4}} \\
   \Mc{\nu = E / h
         \label{eq:P5}} &
      \Ma{\Dfrac{\nu}{E} = 1 / h
         \label{eq:P6}} \\
   \Mc{E = h \nu
          \label{eq:P7}} &
      \Ma{\Dfrac{E}{\nu} = h
          \label{eq:P8}} \\
   \Mc{\nu = c \kappa
         \label{eq:P9}} &
      \Ma{\Dfrac{\nu}{\kappa} = c
         \label{eq:P10}} \\
   \Mc{\kappa = \nu / c
          \label{eq:P11}} &
      \Ma{\Dfrac{\kappa}{\nu} = 1 / c
          \label{eq:P12}} \\
   \\
   \Mc{\lambda = \lambda_0 \left(1 + \frac{Z}{c}\right)
         \label{eq:P13}} &
      \Ma{\Dfrac{\lambda}{Z} = \frac{\lambda_0}{c}
         \label{eq:P14}} \\
   \Mc{Z = c \frac{\lambda - \lambda_0}{\lambda_0}
          \label{eq:P15}} &
      \Ma{\Dfrac{Z}{\lambda} = \frac{c}{\lambda_0}
          \label{eq:P16}} \\
   \Mc{\lambda = \lambda_0 (1 + z)
         \label{eq:P17}} &
      \Ma{\Dfrac{\lambda}{z} = \lambda_0
         \label{eq:P18}} \\
   \Mc{z = \frac{\lambda - \lambda_0}{\lambda_0}
          \label{eq:P19}} &
      \Ma{\Dfrac{z}{\lambda} = \frac{1}{\lambda_0}
          \label{eq:P20}} \\
   \\
   \Mc{\vv = c \beta
         \label{eq:P21}} &
      \Ma{\Dfrac{\vv}{\beta} = c
         \label{eq:P22}} \\
   \Mc{\beta = \vv / c
          \label{eq:P23}} &
      \Ma{\Dfrac{\beta}{\vv} = 1 / c
          \label{eq:P24}} \\[-1mm]
   \hline
\end{tabular}
\end{table}