Evolution of the hydrogen and helium emission line profile of RR Lyr during the night of June 11, 1997. Panel a: two consecutive weak He II 4685.68 Å emissions at φ = 0.894 and φ = 0.900 are assumed to be present. Their intensity above the continuum is 6% and 7%, wich is just slightly higher than the D3 He I emission line. Panel b: three consecutive He I 5875.66 Å emissions with an intensity of ∼5% above the continuum are observed, starting at φ = 0.887. Panel c: variation in the Hα profile that reaches 33% above the continuum. The Blazhko phase and the shock velocity are indicated in the top left corner of panel a) and the pulsation phase is shown in the left corner above each spectrum in panel b). The laboratory wavelength of the spectral line of interest is marked by a vertical line in each panel.