\begin{table}%t1
\caption{\label{t1}Observational parameters.}
\par
%\centerline
{
\begin{tabular}{ccccc}
\hline\hline
$\nu$ & $\lambda$ & $\theta_{b}^{a}$ & $T_{\rm sys}^{b}$ & $\eta_{\rm A}^{c}$ \\
 (GHz) &  (cm)& ($''$)&  (K) \\
\hline
13.5--18.7 &   1.9     &  60--45   &      40                &   0.39--0.32 \\
18.0--26.0 &   1.3     &  45--35  &      70                &   0.33--0.26 \\
27.0--36.7 &   1.0     &  32--23  &      75                &      0.30  \\
41.1--49.7 &   0.7     &  23--19  &     150                &   0.36--0.13 \\
\hline
\end{tabular}}
\medskip
\par
$^a$ Full Width to Half Power (FWHP) beam width in arcsec. 
$^b$ System temperatures in units of antenna temperature ($T_{\rm A}^*$). 
$^c$ Aperture efficiency.
\end{table}