Channel maps for C¹⁷O, starting at 5σ (σ = 6 mJy beam⁻¹ km s⁻¹) and following a step of 4σ. Green contours represent low velocities emission, from −1 to 1 km s⁻¹ (left). Blue and red contours indicate intermediate velocities, from −1 to −5 km s⁻¹ and from 1 to 5 km s⁻¹, respectively (middle). Dark-red and dark-blue contours show high-velocity emission, from −5 to −10 km s⁻¹ and from 5 to 10 km s⁻¹, respectively (right). The black contours represent the continuum emission of Fig. 1 for values of 4 and 15σ (σ = 0.4 mJy beam⁻¹). The yellow and white stars indicate the position of Oph-IRS67A and B, respectively. The black diamond denotes the location of the high-density region. The synthesised beam is represented by a black filled ellipse.