Solar Orbiter crossing of the ion tail of comet ATLAS. Left: overview of the ion-tail encounter starting at the end of 3 June until the end of 4 June. Panel a: magnetic field intensity B (blue) and panel b: plasma density n (red). Panels c and d: magnetic field components. Labels in panel c refer to the four regions A-B-C-D identified in the text and separated by vertical dotted lines. Panels e and f: estimated RPW wind speed V and the associated number density flux, respectively. Panel g: magnetic field cone angle θ_BR and numbered labels indicate intervals of wave activity analysed in Sect. 5. Panel h: STEP ion counts for three selected energy channels in the range of 6–19 keV. The last panel, labelled i, shows a time series of the projection of the magnetic field vector in the plane RT; the length of the arrows is proportional to the intensity of the field in the plane. The dashed red line shows the orientation of the discontinuity between regions C and D resulting from the MVA analysis. The arrows in the top panel indicate the boundaries of the A-B-C structure, as discussed in Sect. 6. Right: diagram of the reconstruction of the magnetic field structure observed in the A-B-C-D regions. The magnetic field vectors of panel h are plotted on top of an approximate Solar Orbiter trajectory through the figure. The dashed orange line encodes the current sheet (CS) of Fig. 4 and its orientation corresponds to that of the red dashed line in panel i.