HST photometry of Cepheid candidates in M101

Variations in the reddening-free Wesenheit parameter (W), which is employed as a proxy for luminosity, are examined as a function of the radial distance from the center of M101 (and thus metallicity). We determine that there is no dependence of the slope on metallicity.

However, the intercept is found to depend on metallicity by {gamma}_VI_=-0.33+/-0.12mag.dex^-1^ and {gamma}_VI_=-0.71+/-0.17mag.dex^-1^ using 2{sigma} and 3{sigma} rejection criteria, respectively. Sigma-clipping impacts the derived metallicity dependence, and the 2{sigma} criterion applied likely mitigates blending, particularly in the crowded inner regions of M101. A metallicity-corrected distance for M101 is obtained from 619 Cepheids ({mu}=28.96+/-0.11), a result that agrees with the recently determined SN Ia distance.