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A proper understanding of the Milky Way (MW) dwarf galaxies in a cosmologicalcontext requires knowledge of their 3D velocities and orbits. However, propermotion (PM) measurements have generally been of limited accuracy and availableonly for more massive dwarfs. We therefore present a new study of thekinematics of the MW dwarf galaxies. We use the Gaia DR2 for those dwarfs thathave been spectroscopically observed in the literature. We derive systemic PMsfor 39 galaxies and galaxy candidates out to 420 kpc, and generally find goodconsistency for the subset with measurements available from other studies. Wederive the implied Galactocentric velocities, and calculate orbits in canonicalMW halo potentials of "low" ($0.8 \times 10^{12} M_\odot$) and "high" mass($1.6 \times 10^{12} M_\odot$). Comparison of the distributions of orbitalapocenters and 3D velocities to the halo virial radius and escape velocity,respectively, suggests that the satellite kinematics are best explained in thehigh-mass halo. Tuc III, Crater II, and additional candidates have orbitalpericenters small enough to imply significant tidal influences. Relevant to themissing satellite problem, the fact that fewer galaxies are observed to be nearapocenter than near pericenter implies that there must be a population ofdistant dwarf galaxies yet to be discovered. Of the 39 dwarfs: 12 have orbitalpoles that do not align with the MW plane of satellites (given reasonableassumptions about its intrinsic thickness); 10 have insufficient PM accuracy toestablish whether they align; and 17 satellites align, of which 11 areco-orbiting and (somewhat surprisingly, in view of prior knowledge) 6 arecounter-orbiting. Group infall might have contributed to this, but nodefinitive association is found for the members of the Crater-Leo group.

Gaia DR2 Proper Motions of Dwarf Galaxies within 420 kpc: Orbits, Milky Way Mass, Tidal Influences, Planar Alignments, and Group Infall