
\begin{table*}
%\textdefsummerwinter{here comes the SUMMER caption
\caption{Heterodyne receivers available for the next summer
observing semester. Performance figures are based on recent
measurements at the telescope. $T^{\ast}_{sys}$ is the SSB system
temperature in the $T^\ast_A$ scale at the nominal center of the
tuning range, assuming average summer conditions (pwv = 7mm) and 45\degr\
elevation. $g_i$ is the rejection factor of the image side band.
$\nu_{IF}$ and $\Delta\nu_{IF}$ are the IF center frequency and
width. }
%winter caption
%\caption{Heterodyne receivers available for the next winter
%observing season. Performance figures are based on recent
%measurements at the telescope. $T^{\ast}_{sys}$ is the SSB system
%temperature in the $T^\ast_A$ scale at the nominal center of the
%tuning range, assuming average winter conditions (4mm pwv) and
%45\degr\ elevation. $g_i$ is the rejection factor of the image side
%band. $\nu_{IF}$ and $\Delta\nu_{IF}$ are the IF center frequency
%and width. Note that the 8 standard receivers can be combined in 4
%different ways.}
%end summer/winter caption
\label{Rxs}
\begin{center}
................Rx....p.....1...2...3...4.....rTg.....IDTr......
%% take the first of the following 2 lines for latex2html (does not
%% digest @{}
%\begin{tabular}{|ccccccccccccl|} \hline
\begin{tabular}{|cc@{\,}c@{}c@{}c@{}cccccccc@{}|} \hline
%\textdefsummerwinter{%here comes the SUMMER table
receiver & polari-- & \multicolumn{4}{c}{combinations} & tuning range
         & $T_{Rx}$(SSB) & $g_i$ & $\nu_{IF}$ & $\Delta\nu_{IF}$
         & $T^{\ast}_{sys}$ & remark \rule{0em}{3ex}\\
  & zation
  &\makebox[1.5em]{1}&\makebox[1.5em]{2}&\makebox[1.5em]{3}&\makebox[1.5em]{4}&
            GHz & K & dB & GHz & GHz & K & \\[0.5ex]\hline
A\,100 & V & 1 & &3& & 80 - 115.5
                     & 60 - 80 & $>20$   & 1.5 & 0.5 & 120  & \rule{0em}{3ex}\\
B\,100 & H & 1& & &4 & 81 - 115.5
                     & 60 - 80 & $>20$   & 1.5 & 0.5 & 120  & 1 \\
C\,150 & V & &2 & &4 & 129  - 183
                     & 70 - 125& 15 - 25 & 4.0 & 1.0 & 200  &  \\
D\,150 & H & &2 &3 & & 129 -  183
                     & 80 - 125& 8 - 17  & 4.0 & 1.0 & 200  & \\[1ex]
A\,230 & V & 1& &3 & & 197  - 266
                     & 85 - 150 & 12 - 17& 4.0 & 1.0 & 450  & 2 \\
B\,230 & H & 1& & &4 & 197  - 266
                     & 95 - 160 & 12 - 17& 4.0 & 1.0 & 450  & 2 \\
C\,270 & V & &2 & &4 & 241  - 281
                     &125 - 250 & 10 - 20& 4.0 & 1.0 & 1000  & 3\\
D\,270 & H & &2 &3 & & 241  - 281
                     &150 - 250 & 9 - 13 & 4.0 & 1.0 & 1000  & 3\\[1ex]
HERA   &H/V & &  & & & 210 -  276
                     & 110 - 380&$\sim 10$& 4.0 & 1.0 & 400  & 2, 4
                                                           \\[0.5ex]\hline
%{%here comes the winter table
%receiver & polar-- & \multicolumn{4}{c}{combinations} & range
%         & $T_{Rx}$(SSB) & $g_i$ &\  $\nu_{IF}$ & $\Delta\nu_{IF}$
%         & $T^{\ast}_{sys}$ & remark \rule{0em}{3ex}\\
%         & ization &\ AB\ &\ CD\ &\ AD\ &\ BC\ &  GHz & K & dB
%         &\  GHz & GHz & K & \\[0.5ex]\hline
%A\,100 & V & 1 && 3 && 80 - 115.5
%                     & 60 - 80 & $>20$   & 1.5 & 0.5 & 120  & 1\rule{0em}{3ex}\\
%B\,100 & H & 1 &&& 4 & 81 - 115.5
%                     & 60 - 80 & $>20$   & 1.5 & 0.5 & 130  & 1 \\
%C\,150 & V && 2 && 4 & 129  - 183
%                     & 70 - 125& 15 - 25 & 4.0 & 1.0 & 200  &  \\
%D\,150 & H && 2 & 3 && 129 -  183
%                     & 80 - 125& 8 - 17  & 4.0 & 1.0 & 200  & \\[1ex]
%A\,230 & V & 1 && 3 && 197  - 266
%                     & 85 - 150 & 12 - 17& 4.0 & 1.0 & 420  & 2 \\
%B\,230 & H & 1 &&& 4 & 197  - 266
%                     & 95 - 160 & 12 - 17& 4.0 & 1.0 & 420  & 2 \\
%C\,270 & V && 2 && 4 & 241  - 281
%                     &125 - 250 & 10 - 20& 4.0 & 1.0 & 900  & 3\\
%D\,270 & H && 2 & 3 && 241  - 281
%                     &150 - 250 & 9 - 13 & 4.0 & 1.0 & 900  & 3\\[1ex]
%HERA   &H/V&&  &    && 210 -  276
%                     & 110 - 380&$\sim 10$& 4.0 & 1.0 & 400  & 2, 4
%                                                           \\[0.5ex]\hline
%end summer/winter table
\end{tabular}
\end{center}
1: tuning range extended to $\geq 72$ GHz under special conditions (see text)\\
2: noise increasing with frequency\\
3: performance at $\nu<275$ GHz; noisier above 275 GHz.\\
4: the V--array of HERA has slighly higher noise which may vary across
the  IF band; it cannot be used \makebox[1.2em]{}for frequencies higher than 241 GHz.
\end{table*}
