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The apparent universality of the luminosity function of globular cluster systems around elliptical galaxies allows such systems to be used as distance indicators. Two specific implementations have been investigated in the past. The first uses the peak of the luminosity function as a standard candle, whereas the second exploits the steepness of the luminosity function and the consequence that the brightest globular clusters around galaxies have comparable absolute magnitudes. The latter technique has the potential to probe distances out to 35,000 km/s and is thus of considerable interest. Here we consider various effects that might lead to variations in the globular cluster luminosity function from one galaxy to another. In particular, we investigate the influence of variations in the mean metallicity of globular cluster systems around elliptical galaxies on the luminosity function. Recent observations have revealed a substantial dispersion in the mean metallicity of globular cluster systems. We discuss the effect of this dispersion on the distances derived using globular cluster systems. We also consider the consequences of age differences between globular cluster systems on derived distances.
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