H i content of UGC 11951 as detected in both Apertif (left) and WHISP (right). The color scale is the same between the two images and the contours are at [2, 4, 8, 16, 32] × 10²⁰ atoms cm⁻². We note that the WHISP data have a smaller beam size as uniform weighting was used; this can also account for the difference in peak column density values between the two images. The Apertif data is from a single beam; mosaicking would further increase the signal in that map.