Hα image of 3C433 and its environment. Left: low surface-brightness emission in the circum-galactic environment of 3C 433, showing the companion galaxy to the south and several Hα emitting regions. The white dots are mostly the residuals of saturated foreground stars that could not be accurately subtracted. The black and dark blue contours show the low- and high-resolution VLA radio continuum images previously shown in Fig. 1. The contour levels are at 0.2, 0.5, 1.0, 1.5, 2.0 mJy beam⁻¹ for the high-resolution data (blue) and 15, 60, 700 mJy beam⁻¹ for the low-resolution data (black). Light blue contours highlight the Hα emission shown in more detail on the right-hand side. The contour levels are at 4.3, 6.4, 12.8, 25.7, 47 percent of the peak intensity. Light-blue dashed line visualizes the direction perpendicular to the Hα structure in the center. Right: Hα emission in the central radio galaxy, shown at two different contrasts.