\begin{table}%t3
%\centering
\par
\caption{\label{tab:fluxes}Flux densities and spectral index.}
\begin{tabular}{l@{\hspace{0.30cm}}
c@{\hspace{0.15cm}}
c@{\hspace{0.15cm}}
c@{\hspace{0.30cm}}
l@{\hspace{0.15cm}}}
\hline\hline \noalign{\smallskip}
PSR &  S$_{350}$ (mJy) & S$_{1380}$ (mJy)  & S$_{2273}$ (mJy) & SI \\
\hline  
J1721$-$2457 & & 0.58(2) & 0.28(3) & --1.5(2)\\
J1745$-$0952 & 1.8(3) & 0.38(3) & & --1.14(12)\\
J1810$-$2005 & & 1.33(2) & 0.95(4) & --0.67(3)\\
J1918$-$0642 & 5.9(6) & 0.58(2) & & --1.67(6)\\
\hline 
\end{tabular}
\tablefoot{These numbers correspond to the WSRT profiles in
Fig.~\ref{fig:profiles}. Measurements of flux densities at~350 and
2273~MHz, and PSR~J1918$-$0642 at 1380~MHz are based on one or two
50~min observations, and therefore should be regarded as
  indicative of the intensities of the pulsars at the observed
  frequencies only. The ranges in flux densities, and consequently,
SI calculations, are now based on the uncertainties in duty cycles.}\vspace{4mm}
 \end{table}