Geometrical model of Fornax A using CLEAN, geometrical modelling image reconstruction, and the flux density versus (u, v) distance plot. Left: CLEAN image of Fornax A. The structure is consistent with that of a point source, convolved with an elliptical beam of size 580 × 1420 μas (indicated with a dashed black ellipse in the bottom-left corner). The contour levels are 1, 5, 30, 50, 75, and 95% of the intensity maximum of 1.7 × 10⁹ K, and the colour scale corresponds to the measured T_B. Right: eht-imaging model of Fornax A. The point source structure is confirmed. The higher values recovered here stem from the fact that, in the geometrical modelling framework, beam convolution is not required and thus the small diameter of the Gaussian component plugged into Eq. (1) increases the corresponding T_B. Notice here that the axes are zoomed in by a factor of ten compared to the left panel. Bottom: Data and their uncertainties (black dots) with the best-fit model overlaid (grey crosses). The preferred flux density level of the single Gaussian component of the model at $S_0^{\text{ehtim}}$ = 47.5 ± 4.8 mJy is clearly visible.