We present results of a field demonstration of the computed tomography imaging spectrometer (CTIS). The CTIS was used to collect a sequence of image cubes of a missile in flight. This instrument is based on computed-tomography concepts and operates in the visible spectrum. Raw image data was recorded at video frame rate and an integration time of 2 msec. An iterative reconstruction of the spatial and spectral scene information from each raw image took 10 seconds. We present representative missile tracking-by- spectrum results.