Aperture photometry and radial velocity. Top: ASAS-SN light curve of GS4, folded using the period p = 5.20906 ± 0.0005 d and t₀ = 2457384.6 HJD. Bottom: corresponding radial velocity of the system as observed by the LT. We do see a 0.04 phase shift between the radial velocity curve and the ASAS-SN light curve, but we have no clear explanation for it (see Sect. 2.1). The blue curves correspond to the best fit model obtained with PHOEBE on the ASAS-SN light curve when fixing the semi-amplitude radial velocity of the system to the one measured from the LT curve (see Sect. 2.2).