GTC/HiPERCAM images of Wl738 in the ɀ filter (upper image) and the i filter (lower image). The position of the Y dwarf is marked with an arrow. The orientation and size of the images are the same as in Fig. 1. W1738 is clearly detected in these two images but not in the other three HiPERCAM filters (r, 𝑔, and u). We note the presence of a galaxy just north of W1738 that is seen in the i filter but not in the ɀ filter. W1738 was much closer to that galaxy in 2014 than in 2021, and the i-band long-slit spectrum obtained with OSIRIS in 2014 suffered from contamination by this galaxy.