Comparison of the NGC 2024 H II region at optical wavelengths and CO(3–2) emission at 8 km s⁻¹. The panel to the top left shows a DSS2-blue image; yellow stars mark the location of the sub-millimetre cores FIR1 to FIR6 (counting from north to south; Mezger et al. 1988), yellow dots mark HOPS protostars in the field, the green line marks the location of the position-velocity cut shown in Fig. 25. The panel to the top right shows the CO(3–2) emission in a single velocity channel at 8 km s⁻¹ (greyscale and contours). The bottom left panel shows an overlay of the CO(3–2) 8 km s⁻¹ velocity channel (using the same contour levels as in the upper right panel) on the DSS2-blue image, the bottom right panel shows a colour-composite image, where the optical DSS2-blue image is shown in the red and green channels, and CO at 8 km s⁻¹ in the blue channel.