Normalised radial profiles of C1R and C2R projected in the ring plane, as observed from the 1.54 m Danish telescope during the 2017 July 23 event. The green points are for the visual channel (0.45–0.65 μm), the red points for the red channel (0.70–1.0 μm). The darker (resp. lighter) error bars are for the 1σ (resp. 3σ) level stemming from the S/N of the target source and the calibrators. Panels a and b: first detection (immersion) and second detection (emersion), respectively. There is agreement between the visual and the red channels in both detections.