\begin{table}%t1
    %\renewcommand{\arraystretch}{1.25}
      \caption{Observational parameters. \label{obspar}}
                 %\centerline
{
         \begin{tabular}{ccccccccc}
            \hline
            \hline
            \noalign{\smallskip}
    Receiver  & $T\rm{_{sys}}^{(a)}$ & \multicolumn{1}{c}{$\tau$} & Tot. integr.  &  \multicolumn{1}{c}{$\rho^{(b)}$} & Telescope & {1$\sigma$} (rms) & Band  &  \multicolumn{1}{c}{Frequency} \\
    frequency &           &      & time (on/off) &            & beam $HPBW$ & noise level    & width &  \multicolumn{1}{c}{resolution} \\
     (GHz)    &  (K)      &      & (min)         &            & ($''$)      & (mK as $T\rm _A^*$) & (MHz) &  \multicolumn{1}{c}{(MHz)} \\
            \noalign{\smallskip}
            \hline
            \noalign{\smallskip}
                  82.720   &   97      & 0.04   &  470        &   0.78 & 29        &  2  & 490  & 0.3 \\  
                 106.355   &   140     & 0.08   &  375        &   0.75 & 23        &  3  & 490  & 0.3 \\
                 130.000   &   217     & 0.08   &  310        &   0.72 & 19        &  4  & 489  & 0.6 \\
                 153.630   &   292     & 0.14   &  585        &   0.68 & 16        &  3  & 488  & 1.3 \\
                 200.885   &   347     & 0.23   &  250        &   0.59 & 12        &  5  & 1023 & 1.0 \\
                 224.519   &   393     & 0.29   &  331        &   0.54 & 11        &  5  & 1023 & 1.0 \\
                 248.170   &   742     & 0.52   &  320        &   0.49 & 10        &  9  & 510  & 1.3 \\
                 272.810   &   762     & 0.40   &  575        &   0.44 &  9        &  7  & 510  & 1.3 \\  
 \hline
         \end{tabular}}
 $^{(a)}$ Average system temperature.
\\ $^{(b)}$ $T^*\rm{_A} = \rho \it{T} \rm{_{mb}}$.
\par
  \end{table}