Accurate Stellar Kinematics at Faint Magnitudes: application to the
  Bootes~I dwarf spheroidal galaxy
  We develop, implement and characterise an enhanced data reduction approach
which delivers precise, accurate, radial velocities from moderate resolution
spectroscopy with the fibre-fed VLT/FLAMES+GIRAFFE facility. This facility,
with appropriate care, delivers radial velocities adequate to resolve the
intrinsic velocity dispersions of the very faint dSph dwarf galaxies.
Importantly, repeated measurements let us reliably calibrate our individual
velocity errors ($0.2 \leq \delta_V\leq 5$ km s$^{-1}$) and directly detect
stars with variable radial velocities. We show, by application to the Bootes-1
dwarf spheroidal, that the intrinsic velocity dispersion of this system is
significantly below 6.5\,km/s reported by previous studies. Our data favor a
two-population model of Bootes-1, consisting of a majority `cold' stellar
component, with velocity dispersion $2.4^{+0.9}_{-0.5}$\,km/s, and a minority
`hot' stellar component, with velocity dispersion $\sim 9$\,km/s, although we
can not completely rule out a single component distribution with velocity
dispersion $4.6^{0.8}_{-0.6}$\,km/s. We speculate this complex velocity
distribution actually reflects the distribution of velocity anisotropy in
Bootes-1, which is a measure of its formation processes.
