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T.A. von Hippel (Gemini Observatory), A. Layden (Bowling Green State University), A. Cool (San Francisco State University), A. Sarajedini (University of Florida)
The RR Lyrae luminosity calibration remains uncertain at a level that compromises their effective use as standard candles. The globular cluster M5 is nearby and rich in RR Lyrae stars. We present deep images of M5 taken with the Hubble Space Telescope, along with preliminary photometry derived from the images. The lower main sequence is well defined, along with a number of white dwarf stars. We present initial fits to the white dwarf sequence that provide a distance estimate to M5. Together with existing photometry of RR Lyrae stars in M5, we estimate the absolute magnitude of the RR Lyrae stars in this cluster. We compare it to recent MV(RR) estimates based on other techniques, and discuss the potential for improvement in this and other white dwarf distance estimates to globular clusters.