Polar orthographic projections of the LVC map (upper) and the IVC map (lower) shown in Fig. 1. The left (right) panel is centred on the north (south) Galactic pole. Longitude increases clockwise (anticlockwise), with the two panels joining at l = 0° and b = 0°. Dotted lines representing constant longitude and latitude are spaced by 30°. The radius from the pole is ∝cos(b), so this projection emphasizes features at high latitude.