Image of the FRII radio galaxy J103025+052430. In the background, we show the Hubble Space Telescope F160W-filter image (D’Amato et al. 2020). Radio JVLA contours (starting from 3σ) at 1400 MHz with 1.5  ×  1.2 arcsec beam (D’Amato et al. 2022) are overlaid in green. The X-ray Chandra diffuse emission above 2.5σ in the soft band (0.5–2 keV) and hard band (2–7 keV) is shown with dashed and solid blue contours, respectively (Nanni et al. 2018; Gilli et al. 2019). Black letters A, B, C, and D mark the main X-ray components as defined in Gilli et al. (2019). Magenta circles mark the MUSE (m1–m5, Gilli et al. 2019) and ALMA (a1–a3, D’Amato et al. 2020) galaxies, which are part of the protocluster at z = 1.7 presented in Gilli et al. (2019). The SDSSJ1030+0524 quasar at z = 6.3 is marked with a cyan circle. The FRII radio galaxy host is marked with a yellow cross. Two galaxy members of the protocluster are located outside the displayed field of view: m6, located at ∼25 arcsec north of m2, and one source detected by LUCI, located at ∼1.5 arcmin south-east of the FRII radio galaxy host.