The objective of this study is the development of a multicolor pyrometer with a very fast response time. Specific objectives for the pyrometer are the capability of measuring temperatures as low as 1200 deg K, a rise time of 50-100 nsec or less, a measurement area of 2 mm dia. Or less, and the elimination of data uncertainties due to an unknown specimen surface emissivity. Although this pyrometer will be a valuable temperature measurement tool in numerous applications, the design will be oriented towards meeting the temperature measurement requirements and physical installation and operation conditions associated with testing conducted in the aedc range/track g hyper-velocity test facility. Phase I of the development effort for this pyrometer was successful in verifying the feasibility of developing this instrument and in identifying components and system parameters which can be utilized in the design. The overall objective in phase II is to continue this development to the point where a prototype instrument has been fabricated and evaluated in full-up testing.