Example channel maps of the primary beam corrected cube of HCG 90 overlaid on enhanced DECaLS optical images. To improve the signal-to-noise ratio of the optical data and highlight the optical tail, we have added G-band and R-band images and aligned the pixel scale to 8×8 (0.27×8 arcsec). Contour levels are (1.5, 2, 3, 4, 5, 6) times the median noise level in the cube (0.66 mJy beam−1). The yellow and green colours show contour levels below 3σ. The red colours represent contour levels at 3σ or higher. Additional figures can be downloaded here.