With the continuing improvements in optical technology, it becomes more and more feasible to use ground based spectrographic observations of the light emitted by the upper atmosphere during the auroral and at twilight to determine the density and composition of the region, and energy inputs from electron precipitation and solar EUV and X-ray absorption. This award is for construction of a state of the art spectrograph using a very large and precisely ruled diffraction grating now available. The sensitivity for weak emissions will be significantly greater than that available previously, and when coupled with new developments in array detectors, an instrument of outstanding capability should result. Observations are planned in conjunction with rocket and radar measurements, and the master grating and final design will be available to the aeronomy community for duplication of the instrument, once the developmental work has been completed.