Left: Spectral time series of AT 2025abao and basic line identification. The spectra are corrected for blueshift and total reddening and are plotted in logarithmic scale. The mid-resolution GTC+OSIRIS spectrum is highlighted in purple, while the NOT+ALFOSC gr7 and gr8 spectra, taken on the same night, are shown in blue and red, respectively. Phases in days are reported on the right side of each spectrum. The regions contaminated by telluric absorptions are identified with cyan bands. Right: Evolution of the Hα profile in the velocity space.