Top: separate 0.86 mm brightness temperatures of Pluto and Charon measured by ALMA on June 12 and 13, 2015 (Butler et al., in prep.), compared to calculations based on the Lellouch et al. (2016) model, and adjusting the absolute 0.86 mm emissivity to 0.71 ± 0.01 for Pluto and 0.76 ± 0.06 for Charon. Bottom: flux density of the Pluto+Charon system for the conditions of the IRAM/NIKA2 observations of Feb. 28, 2017, and two values (0.72 and 0.85) of the system absolute emissivity. The statistical and calibration error bars have been combined quadratically.