Top left: H I column density map of the tails of HCG 90. The contour levels are (0.35, 0.69, 1.38, 2.77) × 10¹⁹ cm⁻². The blue area indicates the slice from which the position-velocity diagram shown at the bottom panel was derived. Top centre: Moment-1 map, the contour levels are (2300, 2320, 2340, 2360, 2380, 2400, 2420, 2440, 2460, 2480, 2500, 2520) km s⁻¹. Top right: Signal-to-noise ratio map. Pixels above 6-σ are all shown in red. The black contour represent the lowest column density contour plotted at the top left panel of the figure. Bottom left: Position-velocity diagram taken from the slice shown at the top right panel. Bottom right: Global H I profile. The black line is a smoothed version of the profile using at 20 km s⁻¹ velocity resolution.