NIR-optical contemporaneous SED of J1023 obtained in this work (orbital phase 0.59; blue squares); the NIR−X-rays SED of J1023 reported in Coti Zelati et al. (2014) is also represented (red dots), with superimposed the fit with a model made by the companion star (red dashed line), the accretion disc (green dash-dotted line), and the shock emission powered by the NS spin-down luminosity (blue dotted line).