Top: ¹²CO(4–3) spectra overlaid on the Herschel dust temperature map. The (0,0) position of the map is α₂₀₀₀ = 12^h 28^m58^s, δ₂₀₀₀ = − 71°16′55′′ Middle: ¹²CO(4–3) spectra overlaid on the northern Herschel column density map. The white contours indicate Musca filament crest (N > 3 × 10²¹ cm⁻²). The black squares indicate the locations of the spectra displayed below. Below: zoom into spectra at selected positions in the map. This shows that there is ¹²CO(4–3) and ¹²CO(3–2) emission at the velocity of the blueshifted component over the full map.