Evolution of Hα (blue) and Hβ (green) region of the spectra in velocity space. Panel a: Before host subtraction. Panel b: Host subtracted. Panel c: Host subtracted and continuum subtracted. The dash-dotted vertical line shows the central wavelength. The colours of the vertical lines denote the different elements, blue is for hydrogen, red for helium, green for the N III and in purple we show the sharp feature at 6353 Å, present only until ∼ + 10 d post-peak. If this feature is a fast moving component connected to Hα, then its blueshift corresponds to ∼9600 km s⁻¹. If Hβ has a similar component with the same velocity, it would appear at ∼4706 Å. A line is indeed seen in these wavelengths but could be associated with He II 4686 Å.