Most of mass estimates of the MW in the outskirts come from measuring motions of stars (just not in the disk of the MW) dwarf galaxies, globular clusters or st

Most of mass estimates of the MW in the outskirts come from measuring motions of stars (just not in the disk of the MW) dwarf galaxies, globular clusters or stellar streams. These measurements have their own issues, but now many of these measurements broadly agree and this new one very is an outlier. Measurements using gas have their own issues, and also they do not go as far away from the galactic centre as the new rotation curve from the paper.