  WFIRST microlensing observations will return high-precision parallaxes,
sigma(pi) < 0.3 microarcsec, for the roughly 1 million stars with H<14 in its
2.8 deg^2 field toward the Galactic bulge. Combined with its 40,000 epochs of
high precision photometry (~0.7 mmag at H_vega=14 and ~0.1 mmag at H=8), this
will yield a wealth of asteroseismic data of giant stars, primarily in the
Galactic bulge but including a substantial fraction of disk stars at all
Galactocentric radii interior to the Sun. For brighter stars, the astrometric
data will yield an external check on the radii derived from the two
asteroseismic parameters, <Delta nu> and nu_max, while for the fainter ones, it
will enable a mass measurement from the single measurable asteroseismic
parameter nu_max. Simulations based on Kepler data indicate that WFIRST will be
capable of detecting oscillations in stars from slightly less luminous than the
red clump to the tip of the red giant branch, yielding roughly 1 million
detections.
