Globular clusters comprising to stars were formed early in the history of the Milky Way, and are scattered throughout the halo. The age of the clusters is about 13 Gyr, with an age spread of less than 5 Gyr . According to the frequently updated catalog of globular cluster properties maintained on the web by Harris , the globular cluster system numbers roughly 150 clusters. Although the list is fairly complete, new globular clusters have been recently discovered at very low galactic latitudes [114, 135], and there is the prospect for a few more clusters to be hidden behind the bulge or out in the far reaches of the galaxy. The distribution of globular clusters in galacto-centric coordinates is shown in Figure 1.
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