\begin{table}%t2 \caption{\label{tab2}System parameters of HD~189733b.} \par %\centerline { \small \begin{tabular}{lllll} \hline\hline Parameter & \multicolumn{2}{c}{\underline{Individual NICMOS Fits}} & \multicolumn{2}{c}{\underline{Joint HST \& Spitzer$^\dagger$}} \\ & $F166N$ filter & $F187N$ filter & $F166N$ filter & $F187N$ filter \\ \hline central wavelength, $\lambda$ ($\mu$m) & 1.6607 & 1.8748 \\ wavelength range, $\Delta\lambda$($\mu$m) & 0.0170 & 0.0191 \\ planet-to-star radius contrast, $R_{\rm pl}$/$R_{\star}$ & 0.15464~$\pm$~0.00051 & 0.15496~$\pm$~0.00028 & $0.15498\pm0.00035$ & $0.15517\pm0.00019$ \\ inclination, $i$ (deg) & 85.75~$\pm$~0.13 & 85.715~$\pm$~0.076 & \multicolumn{2}{c}{85.723~$\pm$~0.024$^\dagger$} \\ system scale, $a$/$R_{\star}$ & 8.871~$\pm$~0.095 & 8.854~$\pm$~0.062 & \multicolumn{2}{c}{8.898~$\pm$~0.027$^\dagger$} \\ impact parameter, $b=a\cos i$/$R_{\star}$ & 0.657~$\pm$~0.021 & 0.661~$\pm$~0.013 & \multicolumn{2}{c}{0.6x636~$\pm$~0.0031$^\dagger$} \\ stellar density, $\rho_{\star}$ (g cm$^{-3}$) & 2.684~$\pm$~0.086 & 2.669~$\pm$~0.056 & \multicolumn{2}{c}{2.709~$\pm$~0.025$^\dagger$} \\ linear limb-darkening coefficient, $c_{2}$ & 2.195~$\pm$~0.058 & 1.972~$\pm$~0.029 & 2.1483 & 1.9508 \\ \hline \end{tabular}}\medskip \par $^\dagger$~System parameter values and 1-$\sigma$ error derived from the weighted mean using: Pont et~al. (2007) HST/ACS, Désert et~al. (2009a,b) Spitzer/IRAC, Knutson et~al. (2009) Spitzer/IRAC, and the individual fits of this work HST/NICMOS. The mean value was adopted for the fits. \end{table}