Top panel: Reduced optical spectra of WPVS 48 during the variability campaign from December 2013 to June 2014. The spectra were calibrated to the same absolute [O III] λ5007 flux of 244 × 10⁻¹⁵ erg cm⁻² s⁻¹. The identified emission features are labelled. Bottom panel: Zoomed-in image of the continuum and the low-intensity emission lines. The conspicuous feature at ∼5490 Å is a residual from night-sky emission.