The Southern Galactic Plane Survey: the Test Region

The Southern Galactic Plane Survey (SGPS) is a project to image the H i line emission and 1.4 GHz continuum in the fourth quadrant of the Milky Way at high resolution using the Australia Telescope Compact Array (ATCA) and the Parkes Radio Telescope. In this paper we describe the survey details and goals, present λ21-cm continuum data, and discuss H i absorption and emission characteristics of the SGPS Test Region (325. 5 ≤ l ≤ 333. 5; −0. 5 ≤ b ≤ +3. 5). We explore the effects of massive stars on the interstellar medium (ISM) through a study of H i shells and the H i environments of H ii regions and supernova remnants. We find an H i shell surrounding the H ii region RCW 94 which indicates that the region is embedded in a molecular cloud. We give lower limits for the kinematic distances to SNRs G327.4+0.4 and G330.2+1.0 of 4.3 kpc and 4.9 kpc, respectively. We find evidence of interaction with the surrounding H i for both of these remnants. We also present images of a possible new SNR G328.6-0.0. Additionally, we have discovered two small H i shells with no counterparts in continuum emission. Subject headings: ISM: structure — supernova remnants: individual: (G327.4+0.4, G330.2+1.0) — H ii regions: individual: (RCW 94) — radio lines: ISM — radio continuum: ISM