Comparison of the GMOS spectra of CHS 7797 at the two observed phases, i.e. maximum (A) and four days before maximum (B) with Upper Scorpius members spectra from Lodieu et al. (2011). The spectra were normalised using the flux at 7500 Å and displaced vertically by an arbitrary constant value. The bottom panel shows the subtraction of the spectra of CHS 7797 at each phase with the best-matched spectra of the UpS members.