Fig. 20.
The differences in the temperature of a high-temperature blackbody determined using ITS-90 (labeled TPEP) and three irradiance filter radiometers (labeled Tfr). The centroid wavelengths of the filter radiometers are 405 nm, 469 nm, and 560 nm, with effective bandwidths of 57 nm, 114 nm, and 107 nm, respectively. The solid lines represent the expanded (k = 2) component of uncertainty from the uncertainty in the freezing point of gold; the dashed lines represent the total expanded uncertainty (k = 2) in the ITS-90 realization.