RVs of the Hα line of γ Cas during the 2020–2022 monitoring campaign. Top panel: RVs of the Hα emission peak. Middle panel: overall RVs as a function of time. The different symbols stand for the methods used to determine the overall RVs: open dots represent first-order moment; red squares the mirror profile; green pentagons the correlation with a two-Gaussian function; and blue triangles the correlation with the February 19, 2021, spectrum. Bottom panel: RVs from the mirror profile and the correlation with two-Gaussian function methods as a function of orbital phase computed with the ephemerides of solution number 5 of Nemravová et al. (2012). The solid line in the bottom panel yields the RV curve of Nemravová et al. (2012) with a systemic velocity set to –10.5 kms⁻¹, whilst the dashed line corresponds to the best-fit orbital solution obtained from our RVs (see the main text and Table 2). The symbols have the same meaning as in the middle panel.