We present ground-based observations of the terrestrial O doublet (2D -- 4S) emission at 3726 and 3729 Å. These O emission lines were detected as part of a Galactic O interstellar medium program underway at the University of Wisconsin's Pine Bluff Observatory using a Field-Widened Spatial Heterodyne Spectrometer (FW-SHS). The FW-SHS produces Fizeau fringes by replacing the return mirrors in a Michelson interferometer with diffraction gratings. The FW-SHS combines interferometric and field-widening gains to achieve sensitivities much larger than conventional grating instruments of similar size and resolving power. We present the initial O FW-SHS observations, believed to be originating in the F region of the ionosphere. The emission intensities are estimated to be in the range of 0.5-1.5 R. Results from several observation periods ranging from December 2003 through October 2005 are discussed. We include the doublet ratio results for all observation periods as well as an implied seasonal variability in intensity. As this terrestrial O emission is a relatively unstudied phenomenon, we outline the methodology we are using to study this doublet and discuss its importance to the F region of the ionosphere.