a) Power spectrum of the Fizeau laboratory fringes obtained using a supercontinuum laser source in the focal plane of the Mertz corrector and a mask positioned on a lens just after it (see L1 Lens in Fig. 3 of Le Coroller et al. 2012a and Fig. 12 of Dejonghe et al. 2014). The diameters of the three holes and their positions in the mask are adjusted using the Zemax ray-tracing code to simulate the three stellar beams coming from the primary mirrors. The mask has been oriented to simulate the stellar fringes at the transit. P1, P2, and P3 indicate the position of the fringe peaks for the 5 m, 9 m, and 10.5 m baselines, respectively. The vertically aligned dots are an artifact of the science camera (visible even when the camera is illuminated uniformly without fringes). b) Sum of all the power spectra computed for Deneb (3000 images recorded before the transit and 10 000 images recorded after the transit: see log of the observations in Table A.1). The Earth rotation correction has turned the “artifacts” of the images taken before the transit counterclockwise, while they turned clockwise for the images taken after the transit. The intensities are represented using a linear scale. We see the Deneb fringe peaks of the 5 m baseline (P1). They are at the expected position with the same shape as in the laboratory (image a) using the green filter (λ = 510 nm, Δλ = 84 nm). The black arrows define the coordinate system of the panel. The f_EW arrow indicates the direction and the norm of the spatial frequency of the 5m baseline (oriented east-west) at 510 nm while the f_NS arrow shows the direction of the spatial frequency of the 10m baseline (oriented north-south). It has the same size as the f_EW arrow.