Figure 5-1: Estimated total spectral measurement uncertainty for global measurements with the integrating spheres on (a) units number 102, 158, and 174; (b) global-normal measurements with the Teflon dome receivers on units 174 and 218; and (c) direct-normal measurements with the view-limiting tubes on units 158, 172, and 174. The measurement uncertainty is symmetrical except in (a) where a -8% bias is included in the lower limit for global-horizontal and global-tilt cases due to nonuniform sphere response when a strong direct-beam component is present.