\begin{table}%T1
\caption{Background sources observed.}\label{t1}
%\centerline
{
\begin{tabular}{lcccc}
\hline\hline
Source&$l$& $b$ & $\sigma_{\rm{l/c}}^1$& $\int\tau(\hocp) {\rm d}v$ \\ 
\hline
&&&&\kms \\
\hline
B0355+508 & 150.38\degr  & $-$1.60\degr  & 0.0022 &  0.042(0.005) \\
B0415+379 & 161.68\degr & $-$8.82\degr  & 0.0029  & 0.051(0.004)\\
B0528+134 &  191.37\degr &$-$11.01\degr  & 0.0101  &  $<$0.036 \\
B1730-130 &  12.03\degr &$+10.81$\degr  & 0.0081  &  $<$0.026  \\
B2200+420 &  92.13\degr &$-$10.40\degr  & 0.0041&  0.017(0.006) \\
\hline
\end{tabular}}
\par
\medskip
$^1$ rms noise in line/continuum ratio at 140 kHz (0.46 \kms) 
resolution.
\end{table}