The Radial Velocity of OGLE-2015-BLG-0966S
  The distance to the planetary system OGLE-2015-BLG-0966L and the separation
between the planet and its host star are ambiguous due to an ambiguity in the
distance to the source star (Street et al. 2016). We attempt to break this
degeneracy by measuring the systemic radial velocity of the source star
measured from a spectrum taken while the source was highly magnified. Our
measurement of v_{LSR} = 53 +/- 1 km s^{-1} does not definitively resolve the
nature of the source, but supports the general conclusion that the source is in
the bulge. Although in this case the measured radial velocity was inconclusive,
this work demonstrates that even a low signal-to-noise spectrum can provide
useful information for characterizing microlensing source stars.
