Missing Galactic PNe: [S III] Imaging Survey

The total number of Galactic planetary nebulae (GPNe) is highly uncertain; the most inclusive current catalog contains only $\sim$ 1,500. We will use the PRISM wide-field imager on the 1.83 m Perkins Telescope to conduct a pilot survey of the Galactic plane in search of [S III] emission from PNe obscured by dust and missed by surveys of H$\,\alpha$. We are employing the method of Jacoby & Van de Steene (JVS), who surveyed the bulge for [S III] $\lambda$9532. In addition to seeing through more of the extinction, use of the [S III] emission line will a priori reject the most troublesome catalog contaminants: ultracompact H II regions.