Identification of galaxies and structures around GS5001. Left: NIRCam three-colour image of GS5001 (F090W filter in blue, F200W filter in green and F444W filter in red). Middle: HST/ACS F775W band image with contours of the NIRSpec [O III] emission in red. In blue are the names of the sources identified in CANDELS. Right: NIRSpec [O III] flux map with contours of the HST ACS/F775W emission in black. Blue and green regions mark the different components identified in the [O III] map, from which we extracted the integrated spectra reported in Fig. 5 and Fig. G.1 in the appendix. The green crosses show the centre of the continuum emission in the HST/WFC3 F125W filter, used for astrometric registration.