Rest-frame UV/optical spectroscopic and photometric data of PJ308-21. The main emission lines are indicated. The aperture-corrected NIRSpec spectrum is shown in red (see Sect. 3.1). The purple and blue lines show MUSE and X-shooter spectra from previous works (Farina et al. 2019; Schindler et al. 2020). We show in gray the X-shooter data affected by the atmosphere absorption. The photometric data from Pan-STARRS1 (PS1; g, r, i, z, Y bands), GROND (i, z, J bands), VHS (Y, H, K bands), Spitzer (Ch1 = 3.5 μm, Ch2 = 4.5 μm), and WISE (W1 = 3.3 μm, W2 = 4.6 μm) are shown with the associated errors (Bañados et al. 2016).