2002AJ....123..473B

We present an absolute parallax and relative proper motion for the fundamental distance scale calibrator, RR Lyrae. We obtain these with astrometric data from FGS 3, a white-light interferometer on the Hubble Space Telescope. We find π_abs=3.82±0.2 mas. Spectral classifications and VRIJHKT₂M and DDO 51 photometry of the astrometric reference frame surrounding RR Lyr indicate that field extinction is low along this line of sight. We estimate <A_V>=0.07±0.03 for these reference stars. The extinction suffered by RR Lyr becomes one of the dominant contributors to the uncertainty in its absolute magnitude. Adopting theaverage field absorption <A_V>=0.07±0.03, we obtain M^RR_V=0.61^–0.11_+0.10. This provides a distance modulus for the Large Magellanic Cloud (LMC) of m-M=18.38-18.53^–0.11_+0.10, with the average extinction-corrected magnitude of RR Lyrae variables in the LMC, <V(RR)>, remaining a significant uncertainty. We compare this result with more than 80 other determinations of the distance modulus of the LMC.