Overview of the M0.8–0.2 ring within the CMZ. Upper-left panel: HNCO (4–3) peak intensity map (12 m, 7 m, and total power array data combined) from ACES towards the M0.8–0.2 ring. The colour scale extends from 0.2 to 8.0 K in square root stretch. The dotted white circles show the approximate extent of the Berschel 250 μm continuum emission of the ring-like structure. The ALMA beam size of 2.8″ is shown in the lower right, and a scale bar of 5 pc is shown in the lower left of the panel. Lower-left panel: HNCO (4–3) emission from the Mopra telescope (Jones et al. 2012). The Mopra beam size of 39″ is shown in the lower right of the panel. Upper-right panel: multi-wavelength view of part of the CMZ. We show a three-colour composite of 8 μm emission from the Spitzer GLIMPSE survey (green; Churchwell et al. 2009), 24 μm emission from the Spitzer MIPSGAL survey (yellow; Carey et al. 2009), and 20 cm emission observed by MeerKAT (red; Heywood et al. 2019, 2022) and the GBT (red; Law et al. 2008). Overlaid as black contours are the total molecular gas column densities at levels of 5, 7.5, 10, 15, 25, and 50 × 10²² cm⁻² (Battersby et al., in prep.) calculated using data from the Herschel Hi-GAL survey (Molinari et al. 2010). Also overlaid are a number of interesting features in the Galactic Centre and the dotted white circles highlighting the ring-like structure (identical to the left panels). The Herschel beam size of 25″ and a scale bar of 15 pc are shown in the lower left of the panel. Lower-right panel: PV diagram of the Mopra HNCO (4–3) emission (Henshaw et al. 2016). Each point corresponds to the longitude and centroid velocity of a Gaussian component of the HNCO emission, extracted using SCOUSE (Henshaw et al. 2016). The emission at the position of the ring-like structure is highlighted with three different colours, corresponding to the velocity ranges <0 km s⁻¹ (blue), 0–70 km s⁻¹ (orange), and >70 km s⁻¹ (red). The orange dots correspond to the M0.8–0.2 ring, while the blue and red dots relate to additional line-of-sight material. The orbital model of Kruijssen et al. (2015) is overlaid as a dashed black line.