\begin{table}%t1
%\centering
\par
\caption{\label{results}Measured SPIRE noise.} 
\begin{tabular}{lcccc} 
\hline\hline \noalign{\smallskip}
Band & $\sigma_{\rm conf}$ & $\sigma_{\rm inst}$ &  \multicolumn{2}{c}{$\sigma_{\rm inst}$} \\  
$\mu$m &~mJy/beam &~mJy/beam$\sqrt{\rm s}$ &  \multicolumn{2}{c}{mJy/beam$\sqrt{\rm repeats}$} \\ 
&&&Nominal\tablefootmark{a}& Fast\tablefootmark{b}\\ 
\hline  
 250     &   5.8   $\pm$ 0.3   & 8.5   $\pm$ 0.4 & 9.0 &    12.7     \\
 350     &   6.3   $\pm$ 0.4   & 9.4    $\pm$ 0.5 & 7.5 &      10.6   \\
 500     &   6.8   $\pm$ 0.4   & 13.3   $\pm$ 0.7  & 10.8 &    15.3   \\
\hline   
\end{tabular} 
\tablefoot{\tablefoottext{a}{30$''$/s scan speed.}
\tablefoottext{b}{60$''$/s scan speed.}} 
\end{table}