Table 2 summarizes the different measurements of the LMC distance published since January of 2002. It is customary to calculate an average final result in a review like this one, and in order to do this I have to make some assumptions about the error bars. Where both random and systematic errors are given, I adopt their (arithmetic) sum as the total error, and I use this to weight the average. Two of the Cepheid-based distance results have incomplete error estimates, and for these I adopt ±0.1 mag (see notes in 3rd column). The result from Kerber et al. (2002) is excluded. The weighted average of 14 measurements is µ0 = 18.50±0.02 mag (standard deviation = 0.04 mag). The reduced chi-squared is less than one, which suggests that the adopted error bars may be too conservative.
A great American sports journalist once said famously, "The opera ain't over till the fat lady sings", to make a point that the outcome of a series of games was not yet determined. Regarding the convergence of published LMC distance results, I suggest to you that the fat lady has begun to sing.
Table 2 demonstrates a remarkably high level of consistency. The possibility that a consensus on the LMC distance has been reached seems much more plausible now than it did when Freedman et al. (2001) reviewed the literature at the conclusion of the HST key project only two years ago. See also Walker (2003) for a recent review of distances to Local Group galaxies.
|Red Clump||18.493 ± 0.033r ± 0.03s||Alves et al. (2002)|
|Red Clump||18.471 ± 0.008r ± 0.045s||Pietrzynski & Gieren (2002)|
|Red Clump||18.54 ± 0.10||Sarajedini et al. (2002)|
|Cepheid||18.48||Bono et al. (2002); ±0.1|
|Cepheid||18.55 ± 0.02r||Keller & Wood (2002); ±0.1|
|Cepheid||18.54 ± 0.29||Benedict et al. (2002)|
|RR Lyrae||18.50 ± 0.07||Clementini et al. (2003)|
|RR Lyrae||18.43 ± 0.06r ± 0.16s||Alcock et al., preprint|
|RR Lyrae||18.55 ± 0.07||Dall'Ora et al. (2003)|
|RR Lyrae||18.48 ± 0.08||Borissova et al., preprint|
|Mira||18.48 ± 0.08||Feast (2003)|
|Main Sequence||18.5 -- 18.7||Kerber et al. (2002); exclude|
|Main Sequence||18.58 ± 0.08||Groenewegen & Salaris (2003)|
|SN 1987A||18.46 ± 0.12||Mitchell et al. (2002)|
|Eclipsing Binaries||18.46 ± 0.08||see Section 5.4|
|Weighted Ave.||18.50 ± 0.02||(s.d.= 0.04)|