\begin{table}%t1
\caption{\label{tab:subsets}Observing runs selected for analysis. }
%\centerline
 {\small \begin{tabular}{cclc}
\hline\hline
UT date & $\mu$ & Coordinates &  $\Delta I_{\rm{rms}}$ [\%] \\
\hline
20/5/2007 08:00 & $0.999 \pm 0.001$ & 0.2S, 0.5E   & 9.2 \\
25/5/2007 08:30 & $0.816 \pm 0.010$ & 26.7N, 22.1E & 5.4 \\
27/5/2007 15:30 & $0.793 \pm 0.012$ & 1.3N, 37.5W  & 6.0 \\
25/5/2007 09:56 & $0.608 \pm 0.020$ & 51.1S, 3.7E  & 4.7 \\
20/5/2007 09:27 & $0.424 \pm 0.024$ & 29.9S, 61.4W & 5.2 \\
25/5/2007 07:40 & $0.197 \pm 0.003$ & 18.0S, 82.4E & 3.4 \\
\hline
\end{tabular}}
\medskip
Coordinates are given in the Heliographic Stonyhurst system. The spread in $\mu$ is given by the approximate spatial coverage of the slit. The $\Delta I_{\rm{rms}}$ is given as the maximum continuum contrast of a single frame in the 615~nm wavelength region.
\end{table}