Different centre positions from this work and the literature. Boxes indicate uncertainty determinations from centres as calculated by other authors. The background images show: continuum emission around the Hα line, rescaled in intensity (left panel, arbitrary units) and the observed stellar velocity field (right panel and horizontal colour bar, not corrected for the systemic velocity). The coordinates of the symbols and the box centres are given in Table A.1. Yellow box (Fabry-Perot kinematic centre, Fathi et al. 2008, Knapen et al. 2010, size of the box: 4.0×4.2 arcsec²); grey box (Pa β kinematic centre, Knapen et al. 2010, size of the box: 9.6×8.0 arcsec²); grey ” (corner of the Pa β uncertainty box that is the furthest away from the centre determined using the MUSE stellar velocity map); purple ” (optical nucleus, Díaz et al. 2006); white ” (MUSE stellar kinematic centre from model (A), this work); black ” (CO kinematic centre from model (β), this work).