Integrated intensity map (3 km s^-1 wide) of the CO(4−3) (colour scale) from the +50 km s^-1 cloud centred at +58 km s^-1 with [CII] (left) and [NII] (right) emission as contours overlaid on the maps. The first contour of the high frequency lines is set at a 5 × σ significance level, with σ the typical noise of the map. The ⋆ symbol represents the position of Sgr A^⋆. The solid straight line shows the position of the Galactic plane at , with marks denoting a few Galactic longitude values for orientation. A prominent [CII] structure is found tangent to the convex side of the +50 km s^-1 cloud with a small [NII] counterpart.