NGC 1566 and NGC 1581. In the top panel is shown the VST image colour composite image (RGB as in Fig. 12) of NGC 1566 and NGC 1581 members (north is on the top and east is to the left, FoV = 6080 × 3137). Their projected separation is 40.84′, while they are separated by 96 km s⁻¹, as shown in the bottom left panel. Bottom right panel: FUV emission of NGC 1566 (13′ × 13′see Fig. 10) extends up to the outer column density of H I at 3.7 × 10²⁰ cm² (red) and, especially in the north region, almost to 0.6 × 10²⁰ cm² (orange) reported by Elagali et al. (2019).