Stray-light simulation of a Euclid/VIS observation in the environment of the Orion belt (, ). Gray transparent circles: stars outside the VIS focal plane and at R < 5° from the center of the FOV. The radius of each circle is log-scaled to the flux of the star in the VIS band. The three largest circles represent the main stars ζ Ori, η Ori, and δ Ori from left to right, respectively. Red points: stars inside the FOV of VIS. Purple circles: stray-light contamination level (infield and outfield) at the F1–F9 focal plane points. The focal plane points closer to the bright stars are gradually more contaminated. To the east (α ∼ 87 ° ), dust extinction from NGC 2024 and Barnard 33 nebulae are visible, diminishing the brightness in the stars in the background. The field was chosen for illustrative purposes because Euclid surveys will not observe these regions deep into the Galactic plane.