\begin{table}%t2
\par
%%\centering

\par
\caption {\label{tab:results}Overview of results from calibrating and imaging three test case data sets with no ionosphere (Undisturbed), self-calibration (SC), field-based calibration (FBC) and SPAM.} 
\begin{tabular}{l c c c}
\hline\hline
Field name & VLSS J0900+398 (simulated) & VLSS J0900+398 (real) & VLSS J1300-208 (real) \\
\hline
\multicolumn{4}{l}{Mean background noise $\sigma$ [\mjybeam]:} \\
Undisturbed &  3.0 & -- &  -- \\
SC          & 10.2 & 71 &  92 \\
FBC         &   -- & 87 & 118 \\
SPAM        &  6.7 & 67 &  68 \\
\multicolumn{4}{l}{Number of sources with a peak flux larger than $5 \sigma$:} \\
Undisturbed & 91 &  -- &  -- \\ 
SC          & 91 & 393 & 374 \\
FBC         & -- & 310 & 285 \\
SPAM        & 91 & 372 & 392 \\
\multicolumn{4}{l}{$5 \sigma$ source fraction with an NVSS counterpart within 80\arcsec:} \\
Undisturbed & 1. &   -- &   -- \\ 
SC          & 1. & 0.83 & 0.60 \\
FBC         & -- & 0.86 & 0.74 \\
SPAM        & 1. & 0.97 & 0.97 \\
\hline
\end{tabular}
\end{table}