How good are RR Lyrae and Cepheids really as Distance Indicators? The\n observational approach

A number of recent technical developments, including the Hipparcos satellite,\nthe Hubble Space Telescope fine guidance sensors and long base line near-IR\ninterferometry has made it possible to employ several largely geometrical\nmethods to determine direct distances to RR Lyrae stars and Cepheids. The\ndistance scale now rests on a much firmer basis and the significant differences\nbetween the distances based on RR Lyrae stars (short) and Cepheids (long) to\nthe LMC have been largely eliminated. The effects of metalicity on the RR Lyrae\nperiod-luminosity (PL) relation in the K-band as well as on the Cepheid PL\nrelation appears to be the main remaining issues but even here empirical\nresults are beginning to show convergence. I review here some of these recent\ndevelopments seen from the perspective of the near-IR surface brightness\nmethod.\n