Injection test for radial velocity measurements in VIS-X IFU data. Upper panel: Original data. Bottom panel: Fake Gaussian signal of the same contrast and same blue shift as the fainter star injected at the same separation but in the opposite direction, shown by the cross marker in white. Before the injection, there is no signal in the first component (K=1) in the upper panel. After the injection, we detected the emission at the supposed blue shift and amplitude in the first component (K=1) in the lower panel.