90% percentile of dust temperature T_90% (left) and median column density (right) of fields as functions of position in the Galaxy. In the lower panels, the X and Y coordinates define positions in the Galactic plane with the Galactic centre at (X,Y) = (0,0), the Sun at (X,Y) = (8400 pc,0), and 0 ≤ l ≤ 180 deg for Y ≤ 0. The shaded arcs are the Carina-Sagittarius arm (I), the local arm (II), and the Perseus arm (III), as parametrised by Hou & Han (2014, their Table 1, three-arm model with all spiral tracers).