The HST Treasury Project on Eta Carinae

This program is valuable for a broad range of stellar and nebular astrophysics, as well as data processing techniques and instrument characteristics. While observing this object's mysterious 5.5-year cycle, we obtained data on several distinct, complex, unfamiliar classes of spectra which cannot be observed well elsewhere. The stellar wind parameters lie outside normal experience, the Weigeit ejecta produce narrow-line spectra, unlike any other known object, and the other spectra re also unusual. Altogether our results pertain to stellar instabilities close to the Eddington limit, extreme stellar winds, unexplored nebular/atomic excitation processes, nebular gas dynamics, and instrument performance.