Establishing the Galactic Centre Distance Using VVV Bulge RR Lyrae
  Variables
  This study's objective was to exploit infrared VVV (VISTA Variables in the
Via Lactea) photometry for high latitude RRab stars to establish an accurate
Galactic Centre distance. RRab candidates were discovered and reaffirmed
($n=4194$) by matching $K_s$ photometry with templates via $\chi^2$
minimization, and contaminants were reduced by ensuring targets adhered to a
strict period-amplitude ($\Delta K_s$) trend and passed the Elorietta et al.
classifier. The distance to the Galactic Centre was determined from a high
latitude Bulge subsample ($|b|>4^{o}$, $R_{GC}=8.30 \pm 0.36$ kpc, random
uncertainty is relatively negligible), and importantly, the comparatively low
color-excess and uncrowded location mitigated uncertainties tied to the
extinction law, the magnitude-limited nature of the analysis, and photometric
contamination. Circumventing those problems resulted in a key uncertainty being
the $M_{K_s}$ relation, which was derived using LMC RRab stars
($M_{K_s}=-(2.66\pm0.06) \log{P}-(1.03\pm0.06)$, $(J-K_s)_0=(0.31\pm0.04)
\log{P} + (0.35\pm0.02)$, assuming $\mu_{0,LMC}=18.43$). The Galactic Centre
distance was not corrected for the cone-effect. Lastly, a new distance
indicator emerged as brighter overdensities in the period-magnitude-amplitude
diagrams analyzed, which arise from blended RRab and red clump stars. Blending
may thrust faint extragalactic variables into the range of detectability.
