Optical spectra from our database, zoomed in on the Balmer Hδ, Hγ, and Hβ transitions. They all show BAs with cores partially filled by the emission line. From bottom to top: J1807 (epoch 3 of dataset A, blue), J1727 (epoch 25, red), J1118 (epoch 1, green), and J1753 (epoch 2, magenta). Telluric bands and DIBs are shown as grey and yellow-shaded regions, respectively. The rest wavelength of the transition is marked with a dashed black line, while dotted blue lines mark velocity shifts of ±2500 km s⁻¹ as a visual reference.