Recent work on Mira variables includes a revised zero-point for the PL calibration based on Galactic globular clusters (Feast et al. 2002), and a new Hipparcos zero-point for thin disk Miras (Knapp et al. 2003). Feast (2003) suggests a best-average PL calibration that leads to µ0 = 18.48 ± 0.10 mag.
5.2. Cluster Main-Sequence Fitting
Kerber et al. (2002) used HST/WFPC2 data for the LMC cluster NGC1831 and main-sequence models to derive µ0 = 18.5 to 18.7 mag. Salaris et al. (2003) used HST/WFPC2 data for the LMC cluster NGC1866 and a Hipparcos subdwarf calibration to derive µ0 = 18.33 ± 0.08 mag. However, Groenewegen & Salaris (2003) subsequently revised the main-sequence-fitted modulus of NGC1866 to µ0 = 18.58 ± 0.08 mag. In this revision, the reddening correction was derived from the colors of the cluster's Cepheids. The field red clump stars around NGC1866 are apparently in front of the cluster.
Mitchell et al. (2002) use the "Spectral-fitting Expanding Photosphere Method" to derive µ0 = 18.46 ± 0.12 mag from observations of Supernova 1987A. They also review previous distance measurements based on this object.
I refer the reader to other papers presented at this meeting for details about measuring distances with eclipsing binaries. In the past 2 years, Fitzpatrick et al. (2002) reported a modulus of µ0 = 18.51 ± 0.05 mag for HV982, Ribas et al. (2002) found µ0 = 18.38 ± 0.08 mag for EROS1044, Fitzpatrick et al. (2003) found µ0 = 18.18 ± 0.09 mag for HV5936, and Clausen et al. (2003) found µ0 = 18.63 ± 0.08 mag for HV982. The weighted average is µ0 = 18.46 ± 0.08 mag in good agreement with the standard modulus. However, the standard deviation is about twice as large as the average reported error bar. Possibly the error bars are too optimistic. I speculate that an unknown systematic error may affect the eclipsing binary distance results.