Montage of posterior distributions from performing retrieval on the measured spectrum of HR 8799b and allowing the radius, surface gravity, and mean molecular weights to be uniform or log-uniform priors. The retrieved value of the radius (﹩R\approx 0.5\,{R}_{{\rm{J}}}﹩) is unphysical (see the text for a discussion). The labels “CO,” “CO2,” “CH4,” and “H2O” refer to the mixing ratios of carbon monoxide, carbon dioxide, methane, and water, respectively. R and ﹩{T}_{\mathrm{int}}﹩ are in units of ﹩{R}_{{\rm{J}}}﹩ and K, respectively. The labels “﹩{\kappa }_{0}﹩” and “gravity” are for ﹩\mathrm{log}{\kappa }_{0}﹩ and ﹩\mathrm{log}g﹩ in mks and cgs units, respectively.