- The “Mise en pratique for the definition of the kelvin” (MeP-K) was established in April 2006 to be the repository of information required to perform a “practical measurement of temperature in accordance with the International System of Units (SI).” This article describes the progress made by the MeP-K HT (High Temperature Task Group) of CCT-WG5 (radiation thermometry) in drawing together the appropriate methods for accessing thermodynamic temperature above the silver point involving direct radiometric measurements on the one hand and indirect extrapolation, interpolation, and least-squares fitting on the other. An examination of the uncertainties and a brief discussion of the advantages and disadvantages of the various approaches are given. A summary of the remaining issues to be resolved concludes the article.
