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The 10th recorded outburst of the recurrent eclipsing nova USco was observedsimultaneously in X-ray, UV, and optical by XMM-Newton on days 22.9 and 34.9after outburst. Two full passages of the companion in front of the nova ejectawere observed, witnessing the reformation of the accretion disk. On day 22.9,we observed smooth eclipses in UV and optical but deep dips in the X-ray lightcurve which disappeared by day 34.9, then yielding clean eclipses in all bands.X-ray dips can be caused by clumpy absorbing material that intersects the lineof sight while moving along highly elliptical trajectories. Cold material fromthe companion could explain the absence of dips in UV and optical light. Thedisappearance of X-ray dips before day 34.9 implies significant progress in theformation of the disk. The X-ray spectra contain photospheric continuumemission plus strong emission lines, but no clear absorption lines. Bothcontinuum and emission lines in the X-ray spectra indicate a temperatureincrease from day 22.9 to day 34.9. We find clear evidence in the spectra andlight curves for Thompson scattering of the photospheric emission from thewhite dwarf. Photospheric absorption lines can be smeared out during scatteringin a plasma of fast electrons. We also find spectral signatures of resonantline scattering that lead to the observation of the strong emission lines.Their dominance could be a general phenomenon in high-inclination systems suchas Cal87.

From X-ray dips to eclipse: Witnessing disk reformation in the recurrent nova USco