Evolution of the Hα line profiles of RR Lyrae corresponding to night November 6, 2015. The pulsation phases are indicated on the right side and vary from φ = 0.880 (top right) to φ = 1.089 (bottom right), while the Blazhko phase ψ at the beginning of the observing interval is 0.53. The exposure time is 300 s and weak absorption features are telluric lines. The vertical line represents the Hα line laboratory wavelength (zero velocity) in the stellar rest frame. The profiles are arbitrarily shifted in terms of flux.