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WHAM can reveal emission nearly a 100-million times fainter than the Orion Nebula, making it unsurpassed for collecting high-resolution, optical-line spectra from faint, diffuse sources. Here, we embark on a diverse observational program using multiple optical emission lines with this powerful, remotely-controlled, Fabry-Perot instrument to substantially advance our understanding of interstellar matter and processes that shape it. In previous work, we released the first spectral survey of the Galaxy's DIG with observations of the Balmer-alpha optical emission line of hydrogen. This effort, the WHAM Sky Survey (WHAM-SS), complements neutral gas surveys of the 21-cm radio emission line. The WHAM-SS reveals ionized gas that can be seen in every direction from our location inside the Galaxy and offers a comprehensive view of the distribution and dynamics of the Milky Way's ionized gas. Using different instrument configurations, we are now surveying the southern sky in other emission lines, allowing us to measure physical conditions within the same ionized component.

NSF AST-2009276