\begin{table}%t5 \caption{\label{TabAIR}Infrared line fluxes $I$ and their ratios $I/I$(5007~\AA) to the dereddened optical [\ion{O}{iii}] 5007~\AA\ line from the \emph{Spitzer} data.} %\centerline {\small \begin{tabular}{llllllllllll} \hline\hline\noalign{\smallskip} Line & \multicolumn{5}{c}{Line flux $I$, $10^{-13}$~erg/cm$^2$/s/pixel} & \multicolumn{5}{c }{Flux ratio $I/I$(5007~\AA)} \\ & FMK 1 &FMK 2 &FMK 3 &FMK 4 &FMK 5 & Average & FMK 1 &FMK 2 &FMK 3 &FMK 4 &FMK 5\\ \hline {}[\ion{Ar}{ii}] 6.985~$\mu$m & 3.8 & 14 & 17 & 5.6 & 11 & 0.5(1) &0.41 &0.75 &1.15 &0.46 &0.79 \\ {}[\ion{Ar}{iii}] 8.991~$\mu$m & 0.46 & 2.0 & 1.7 & 0.80 & 1.5 & 0.08(3) &0.05 &0.13 &0.12 &0.07 &0.12 \\ {}[\ion{S}{iv}] 10.51~$\mu$m & 0.24 & 1.6 & 1.4 & 0.67 & 0.91 & 0.07(2) &0.025 &0.11 &0.10 &0.06 &0.07 \\ {}[\ion{Ne}{ii}] 12.81~$\mu$m & 0.31 & 0.92 & 0.89 & 1.0 & 0.30 & 0.10(8) &0.04 &0.07 &0.07 &0.08 &0.025\\ {}[\ion{Ne}{v}] 14.32~$\mu$m & 0.071& 0.20 & 0.18 & 0.10 & 0.14 & 0.012(7) &0.009 &0.012 &0.012 &0.009 &0.014\\ {}[\ion{Ne}{iii}] 15.56~$\mu$m & 0.29 & 2.2 & 1.2 & 3.0 & 0.47 & 0.05(3) &0.009 &0.03 &0.03 &0.05 &0.006\\ {}[\ion{Fe}{ii}] 17.94~$\mu$m & 0.16 & 0.90 & 1.3 & 1.8 & 0.87 & 0.03(2) &0.005 &0.015 &0.03 &0.04 &0.013\\ {}[\ion{S}{iii}] 18.71~$\mu$m & 0.82 & 5.0 & 5.2 & 2.5 & 4.2 & 0.08(2) &0.025 &0.08 &0.15 &0.05 &0.06 \\ {}[\ion{O}{iv}] 25.91~$\mu$m & 2.3 & 13 & 11 & 12 & 7.2 & 0.20(5) &0.08 &0.24 &0.26 &0.26 &0.13 \\ {}[\ion{S}{iii}] 33.48~$\mu$m & 0.28 & 1.9 & 2.3 & 0.76 & 0.6 & 0.04(1) &0.011 &0.05 &0.06 &0.015 &0.015\\ {}[\ion{Si}{ii}] 34.81~$\mu$m & 1.0 & 3.7 & 3.9 & 1.7 & 1.7 & 0.07(3) &0.04 &0.10 &0.11 &0.03 &0.04 \\ \hline \end{tabular}} \medskip The column ``average'' contains the ratio values averaged over the northern part of Cas~A and their observed scatter, and other columns contain data for the \citet{HF96} FMKs.\\ {Notes}: the table contains data for the strongest lines only. The regions are numbered as in \citet{HF96} with their positions shown in Fig.~\protect\ref{FigIRvsHST}. The ``average'' column assumes single optical line reddening correction of 200~times. Note that the pixel sizes are different for the IRS~LL (5\farcs08 or $6.06 \times 10^{-10}$~sr, $\lambda > 15$~$\mu$m) and SL (1\farcs85 or $8.04 \times 10^{-11}$~sr, $\lambda < 15$~$\mu$m) modules. \end{table}