RR Lyrae and Type II Cepheid Variables Adhere to a Common Distance
  Relation
  Preliminary evidence is presented reaffirming that SX Phe, RR Lyrae, and Type
II Cepheid variables may be characterized by a common Wesenheit
period-magnitude relation, to first order. Reliable distance estimates to RR
Lyrae variables and Type II Cepheids are ascertained from a single VI-based
reddening-free relation derived recently from OGLE photometry of LMC Type II
Cepheids. Distances are computed to RR Lyrae (d~260 pc), and variables of its
class in the galaxies IC 1613, M33, Fornax dSph, LMC, SMC, and the globular
clusters M3, M15, M54, omega Cen, NGC 6441, and M92. The results are consistent
with literature estimates, and in the particular cases of the SMC, M33, and IC
1613, the distances agree with that inferred from classical Cepheids to within
the uncertainties: no corrections were applied to account for differences in
metallicity. Moreover, no significant correlation was observed between the
distances computed to RR Lyrae variables in omega Cen and their metallicity,
despite a considerable spread in abundance across the sample. In sum, concerns
regarding a sizeable metallicity effect are allayed when employing VI-based
reddening-free Cepheid and RR Lyrae relations.
