Moment-zero images of multiple-J CO transitions. Big crosses mark the central position of Circinus; small crosses in the upper panels denote the sampled positions. Upper left: ¹²COJ = 3 → 2; upper right: ¹²COJ = 4 → 3; lower left: ¹²COJ = 6 → 5; lower right: ¹²CO J = 7 → 6. Circles in the lower left of each panel show the beam. The ¹²COJ = 7 → 6 map was convolved to an angular resolution of 18′′. Contour levels are 20, 60, ..., 180 Kkms^-1in steps of 40 Kkms^-1 for ¹²COJ = 3 → 2, J = 4 → 3, and J = 6 → 5, and 10, 20, 30 Kkms^-1 for ¹²COJ = 7 → 6 (1σ = 1.9, 3, 10, and 3 Kkms^-1 for ¹²COJ = 3 → 2, J = 4 → 3, J = 6 → 5, and J = 7 → 6). Red (thick dotted) contours present the half maximum level of all images. The thin dotted lines in the lower two panels denote the regions that have been scanned with higher S/N than other regions farther away from the centers (see Sects.2 and 3.1.3). The outer dotted lines in the ¹²COJ = 7 → 6 map are related to masking.