Evolution since 2006 of the EW and FWHM measurements of the H_α emission line. The red dashed vertical lines denote the beginning and the end of the optical outburst seen in ROTSEIIId light curve (see also Fig. 1), whereas the black dashed line shows the time of the turning point (≈ 10 d) from decreasing to increasing trend just after the strong X-ray outburst around MJD ≈ 54 850.