\begin{table}%t1 \caption{\label{Tab:Obs}Details of the imaging observations used in this work.} %\centerline {\begin{tabular}{llllll} \hline \hline \noalign{\smallskip} Date & $\lambda_{\rm central}$ & $\Delta\lambda$ & $N^{{a}}$ & NDIT$^{{b}}$ & DIT$^{{c}}$\\ & [$\mu$m] & [$\mu$m] & & & [s] \\ \hline 29 April 2006 & 1.66 & 0.33 & 32 & 28 & 2 \\ \hline \end{tabular}} \par \smallskip $^{{a}}$ Number of (dithered) exposures $^{{b}}$ Number of integrations that were averaged on-line by the read-out electronics $^{c}$ Detector integration time. The total integration time of each observation amounts to $N\times {\rm NDIT} \times \rm DIT$. \end{table}