Estimating the bar length and corotation radius. Left panel: bar length estimated by fitting ellipses to isodensity contours. The vertical dashed lines denote the estimated bar length. Middle panel: ellipticity and position angle as a function of the semi-major axis of the ellipses. The bar length is the lesser of the two following values: the radius of the first minimum after the ellipticity maximum (dot-dashed orange line) or the radius at which there is the first extremum in position angle outside the bar (dashed line). Right panel: bar corotation radius (marked by the vertical dashed blue line), the radius at which stars in the disc have the same angular frequency (solid black line) as the bar pattern speed (horizontal dashed blue line). The dashed and dot-dashed lines denote the Ω − κ/2 and Ω + κ/2 curves for the galaxy, respectively.