a) First moment radial velocity curves (RV_c) associated with the 17 lines of Table 2. The γ-velocity associated with the cross-correlated radial velocity curve, RV_cc−g in Fig. 2a, has been removed from these curves, i.e., V_γ = −16.95km s^-1 . The γ offset residuals are known to be related to the k-term (Nardetto et al. 2008). The residuals between the RV_c curves and the RV_cc−g in Fig. 2a (resp. RV_cc−c) are plotted in panel b) (resp. c)) after correcting each RV_c curve from its V_γ value.