Discrete Source Detections in the GBT Diffuse Ionized Gas Survey

We analyze discrete sources of Hnα ionized gas emission from the Green Bank Telescope (GBT) Diffuse Ionized Gas Survey (GDIGS). GDIGS is a large survey of ionized gas in the inner Galactic midplane as traced via radio recombination line (RRL) emission in the 4–8 GHz frequency range, with a nominal survey zone of 32.3° > ℓ > −5°, | b | < 0.5°. Using data from GDIGS, we identify and characterize RRL emission from 88 H II regions that previously lacked reported ionized gas velocity measurements. We also identify and characterize RRL emission from eight locations that appear to be previously unidentified H II regions and 37 locations of RRL emission that do not appear to be H II regions based on their lack of mid-infrared emission. These latter locations may represent a compact component of Galactic Diffuse Ionized Gas (DIG). There are an additional 10 discrete RRL locations that have anomalously high RRL velocities for their locations in the Galactic plane. Like the possible compact DIG objects, these sources do not have the expected mid-infrared emission characteristic of H II regions. Based on available evidence we do not think these objects are H II regions, but we are unable to classify them as a known type of object.