Comparison of measured and theoretical geometric albedos of HD 189733 b. The blue dotted line denotes the upper limit for the geometric albedo A_g = 0.12 as measured by Evans et al. (2013) in the HST STIS bandpass. The red shaded region denotes our CHEOPS albedo measurement (±lσ). The blue dashed, red, and green curves respectively denote for HST STIS, CHEOPS, and TES S the theoretically calculated albedos A_g integrated over the respective bandpasses for different X_Na abundances. HST STIS and CHEOPS measurements are consistent with each other if X_Na ≥ 6 × 10^¯6. The corresponding TES S albedo would be very low, and thus undetectable according to the model used here.