Face-on view of the 1^st Galactic quadrant showing the GRS coverage (beige shaded area), and the positions of the Sun (Sun symbol) and Galactic centre (black dot). Dotted black lines indicate distances to the Sun in 2.5 kpc intervals. Left panel: positions of Galactic features as determined by Reid et al. (2019). Spiral arms are shown with green solid lines and the shaded green areas indicate ~ 3.3σ widths of the arms. Spurs are shown with dashed black lines. The features are labelled as follows: 3 kpc far arm (3kF), Aquila Rift (AqR), Aquila Spur (AqS), Local arm (Loc), Local spur (LoS), Norma 1st quadrant near and far portions (N1N, N1F), Outer (Out), Perseus (Per), Scutum near and far portions (ScN, ScF), Sagittarius near and far portions (SgN, SgF). Right panel: position and uncertainties in distance of 71 maser sources overlapping with the GRS coverage. Spiral arm and spur positions are the same as in the left panel.