Presentation #116.60 in the session Stellar/Compact Objects.
RS Ophiuchi is a recurrent nova consisting of a massive white dwarf and a red giant (RG) donor star in a binary orbit of 453.6 days. It underwent its recent outburst on 8 August 2021 and was monitored extensively by NICER. The rapidly evolving NICER spectrum consisted of both line and continuum emission which we modelled using non-equilibrium ionization collisional plasma models. The evolution of the X-ray spectrum is consistent with the nova ejecta driving a forward shock in the dense stellar wind of the RG star.