Shown in colour-scale: intensity-weighted first moment map of the C¹⁸O emission towards AFGL 2591. The corresponding velocities are shown on the colour-bar on the right. The black open circle represents the position and size of VLA 1 at 3.6 cm. The crosses indicate the position of VLA 2 and VLA 3. A scale size of 20 000 AU is represented by a bar in the upper left-hand corner. Shown in contours: the C¹⁸O integrated intensity map from –2.3 to –8.7 km s^-1. The peak flux of the integrated intensity map is 2.5 Jy beam^-1 km s^-1. Contours are at –3, 3, 4, 5, 6, 7    ×    σ = 0.33 Jy beam^-1 km s^-1. The synthesised beam is shown in the lower right-hand corner (4.5′′ ×  3.6′′, PA 93°). The rest velocity of the cloud is –5.7 km s^-1.