Left panel: average profiles of PA (top panel) and ellipticity (bottom panel) obtained with ELLIPSE from the Ks-band image plotted against the isophote major axis. The red points are the measured ellipticity values from the deprojected image (see Sect. 4.2). Right panel: a4 and b4 coefficients of the fourth harmonic term in the Fourier series fit to the isophote deviations from pure ellipses. The average error on ellipticity is ~0.002 and on the PA is ~4 deg. The long-dashed lines delimit the regions where the main components of the galaxy structure are located.