Top: fan-shaped η Car image at velocity of − 277 km s^-1 (image from Fig. 4). The FOV of the image is 50 × 50 mas (118 × 118 au; the center of the continuum region is at coordinate zero). Contour lines are plotted at 8, 16, 32, and 64% of the peak intensity. The PA of the symmetry axis of the fan is ~126° (white arrow). The fan-shaped structure extends ~18.8 au (8.0 mas; blue arrow) to the SE and ~13.6 au (5.8 mas) to the NW, measured with respect to the center of the continuum wind along the fan symmetry axis at the 16% intensity contour. For comparison, the radius R_∗ of the primary star of η Car is ~100 R_⊙ ~ 0.47 au ~ 0.20 mas (R∗ is not well known; Hillier et al. 2001). Therefore, the huge wind extension to the SE is about 40 times larger than R_∗. Bottom: overlay of a sketch of the orbit of the secondary star relative to the primary star on the sky (yellow) and the fan-shaped image at − 277 km s^-1. The orbit is adopted from Teodoro et al. 2016 (phase 0.91 computed as described in this paper). The two red dots are the primary and the secondary star at the time of our observations. The binary separation and PA were approximately 4.9 mas (11.5 au) and 315°, respectively, at the time of observation (Sect. 4). The blue arrow indicates the motion direction and the bar at the bottom right the length of the major axis of the orbit (30.9 au; Madura et al. 2012).