The Milky Way's halo in 6D: Gaia's Radial Velocity Spectrometer
  performance
  Gaia's Radial Velocity Spectrometer (RVS) has been operating in routine phase
for over one year since initial commissioning. RVS continues to work well but
the higher than expected levels of straylight reduce the limiting magnitude.
The end-of-mission radial-velocity (RV) performance requirement for G2V stars
was 15 km/s at V = 16.5 mag. Instead, 15 km/s precision is achieved at 15 < V <
16 mag, consistent with simulations that predict a loss of 1.4 mag. Simulations
also suggest that changes to Gaia's onboard software could recover ~0.14 mag of
this loss. Consequently Gaia's onboard software was upgraded in April 2015. The
status of this new commissioning period is presented, as well as the latest
scientific performance of the on-ground processing of RVS spectra. We
illustrate the implications of the RVS limiting magnitude on Gaia's view of the
Milky Way's halo in 6D using the Gaia Universe Model Snapshot (GUMS).
