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We present an analysis of Galactic bulge stars from Hubble Space Telescope(HST) Wide Field Camera 3 (WFC3) observations of the Stanek window(l,b=[0.25,-2.15]) from two epochs approximately two years apart. This datasetis adjacent to the provisional Wide-field Infrared Survey Telescope (WFIRST)microlensing field. Proper motions are measured for approximately 115,000 starsdown to 28th mag in V band and 25th mag in I band, with accuracies of 0.5 masyr$^{-1}$ (20 km s$^{-1}$) at I $\approx$ 21. A cut on the longitudinal propermotion $\mu_l$ allows us to separate disk and bulge populations and producebulge-only star counts that are corrected for photometric completeness andefficiency of the proper-motion cut. The kinematic dispersions and surfacedensity in the field are compared to the nearby SWEEPS sight-line, finding amarginally larger than expected gradient in stellar density. The observed bulgestar counts and kinematics are further compared to the Besan\c{c}on, Galaxia,and GalMod Galactic population synthesis models. We find that most of themodels underpredict low-mass bulge stars by $\sim$33% below the main-sequenceturnoff, and upwards of $\sim$70% at redder J and H wavebands. Whileconsidering inaccuracies in the Galactic models, we give implications for theexoplanet yield from the WFIRST microlensing mission.

Comparing Observed Stellar Kinematics and Surface Densities in a Low Latitude Bulge Field to Galactic Population Synthesis Models