From top to bottom: initial disc model, disc after PCA reduction without noise, residuals remaining after the disc model was subtracted from the data cubes and the cubes were re-reduced. The colour scale is linear and two times larger for the initial model than for the other two images. The green circles have a radius of 0.4″ and the black arrows indicate the apparent midplane (PA = 29°) with a total length of 6″.