Locations of the newly found OCs younger than 20 million years projected onto the Galactic plane, including their 1σ distance uncertainties. The sizes are proportional to the number of members of each cluster. The solid and dashed curved lines denote the arm centre and widths (i.e., which enclose 90% of the masers), respectively, fitted by Reid et al. (2019) from their parallax data of Very Long Baseline Interferometry masers. The Galactic Centre (red symbol) is at (0, 0) kpc and the Sun (black symbol) is at (0, 8.15) kpc.