Maps of the RW Aur system observed by Rodriguez et al. (2018). Left: ¹²CO zeroth moment. The colour scale has the peak flux as the maximum, and two times the image rms as minimum. Right: ¹²CO first velocity maps created with bettermoments quadratic method (Teague & Foreman-Mackey 2018) and with a 4-sigma clipping process. The image scaled so that the maximum and the minimum are equal to the systemic velocity of the primary target ±2 km s⁻¹.