Average spectra of J1910 during outburst from the first (upper; blue) and second (lower; red) nights, obtained with ACAM after continuum normalisation. The Balmer series down to Hδ is visible, exhibiting both emission and absorption components. Zoomed-in regions show the areas around Hα and Hβ. He I and He II lines are also present and identified in the spectra, along with several diffuse interstellar bands marked with orange bars.