Comparison of the 2MASS JHK_S colour image (top left), normalized column density map (top right), column density map (bottom left) and COHRS ¹²CO (3–2) velocity-integrated image (bottom right) in a low-density region of the Gp centred at (l, b) = 16°, 0°. The original column density is displayed in logarithmic scale and spans the range 3 × 10²¹ to 5 × 10²² cm⁻². The COHRS image is represented in a linear scale with an intensity that spans the range of 0–70 K km/s.