\begin{table}%t4
\caption{\label{tab_fluxvar}The published single-dish flux densities at 5~GHz
    to investigate the source variability.
(1)~observed at 4.9~GHz and corrected to 5~GHz via a
spectral index \protect\( \alpha ^{\rm 10.7~GHz}_{\rm 2.7~GHz}\protect \);
(2)~at~4.85~{\rm GHz}; (3)~at~4.75~{\rm GHz}; (a): K{\"u}hr et~al.~(\cite{hr1981}); (b): Gregory et~al.~(\cite{Gregory1996}); (c):~Gregory \& Condon~(\cite{Gregory1991}); (d):~Reich et~al. (\cite{Reich2000}).}
%\centering
\par
\begin{tabular}{cccc}
    \hline \hline
    $ S_{\rm 5~GHz}[{\rm mJy}] $& Date of observation & Ref. &  Ann.\\
    \hline  
     778~$\pm$~4   & between Feb. 1977 and Mar. 1978 &  (a) &  (1)\\
     788~$\pm$~31   &  Nov. 1986 & (b) & (2)\\
     953~$\pm$~73   & Oct. 1987  & (c) & (2)\\
     623~$\pm$~56   & 1992.5 = Jul. 1992 &(d)& (3)\\
    \hline
\end{tabular}
\end{table}