Large-scale structure around FGS28. Galaxies with SDSS spectroscopy within ±1500 km s⁻¹ from the redshift of FGS28 are represented in black. Moreover, in the bottom-left panel, the large red, green, and blue ellipses represent 5, 50, and 100 Mpc respectively (as in Fig. A.1). The small violet, brown, green, and blue ellipses are the four clusters that are found close to FGS28. In the top-right panel, a zoom can be seen, were the colour coding is the same with the exception of the red ellipse, which now simply identifies the position of FGS28. In this panel, the legend associates each coloured ellipse to a specific clusters. It can be seen that FGS28 is identified by a single galaxy with spectroscopic redshift in SDSS, supporting the notion that this is a isolated galaxy located in the environment of a large supercluster.