Extended Data Fig. 2: Favourite orbital solutions for the C-19 stream.

The dashed line shows the orbit of C-19 constrained using the proper motions (red symbols in a, b) of C-19 members identified by STREAMFINDER, their Gaia parallaxes (c), their radial velocities when available (d) and their location on the sky compared with the distribution of extinction⁴⁵ (e). The orbit determined without using the Gaia parallax information but instead anchoring the distance at 18 kpc is represented by the dotted line. f, g The two orbits, integrated for ±1 Gyr, projected on the Galactic plane, and in the R–z plane. The thick red lines correspond to the part of the orbits that overlaps the observed C-19 member stars.