Our ultimate goal is to compare the radiation temperatures seen by the witness plate and DANTE.
A higher-order comparison involves the spectra incident on the two locations.
DANTE is much farther from the source in the experiment than is the witness plate, resulting in a spectrum much colder, or lower, than the spectrum of the witness plate (Figure 11).  To make a meaningful comparison, we can boost up the spectrum seen by DANTE (Figure 12), according to the temperature that would be obtained if the observed radiation filled 2p steradians.
Figure 11
Figure 12