Left: normalised spatial distribution for cluster Fornax 4 with a stellar density according to King profile fits from Mackey & Gilmore (2003b). The green (dashed) circle indicates the tidal radius. Right: spatial distribution for the cluster convolved with the actual coverage of the HST pointing, and the rejection of a central region due to incomplete data. Comparison between the two distributions allows us to determine the fraction of stars (and therefore mass) missing from the adopted sample.