Moments 0 (left column) and 1 (right column) for C¹⁷O, H¹³CO⁺, C³⁴S and the C₂H N = 4 − 3, J = 9∕2− 7∕2 doublet, above 5σ ( =15 mJy beam⁻¹ km s⁻¹, = 10 mJy beam⁻¹ km s⁻¹, = 10 mJy beam⁻¹ km s⁻¹ and = 15 mJy beam⁻¹ km s⁻¹). Each σ was calculated using the following formula: σ = rms × ΔN × (N)^0.5, where ΔN and N are the channel width and number of channels, respectively. Black contours in moment 0 maps represent the continuum emission from Fig. 1, for values of 4 and 15σ. Black contours in moment 1 maps show σ values of their respective moment 0 maps, being 10, 15 and 20σ for C¹⁷O and C₂ H, 10, 20 and 30σ for H¹³CO⁺, and 6 and 8σ for C³⁴S. The green and white stars indicate the position of Oph-IRS67A and B, respectively. The black diamond denotes the location of the offset region. The synthesised beam for each species is represented by a black filled ellipse.