\begin{table}%t4
%\begin{center}
\par
  \caption{\label{vtor-spectra}  Optical spectra representative of the
    $V/R$-cycle. {\sc flash} is the predecessor instrument of HEROS,
    i.e.\ the same instrument before the extension with a blue
    channel.}
\begin{tabular}{cccc}
\hline\noalign{\smallskip}
\hline
  Spectrum &  [JD~24...]  &  Instrument & Comment  \\
%
\hline 
A & 53~333.8  &  UVES/ESO Archive    &  nightly average \\
B & 52~009.3  &  {\sc heros}/Data Set C   &  single spectrum  \\
C & 53~700.8  &  UVES/ESO Archive         &  night average \\
D & 52~364.3  &  {\sc heros}/Data Set C   &  single spectrum  \\
E & 52~725.3  &  {\sc heros}/Data Set C   &  single spectrum  \\
F & 48~347.6  &  {\sc flash}/LSW Archive     & single spectrum   \\
\hline 
\end{tabular}
\end{table}