In WIKIPEDIAOn Wikipedia, Therethere are two namenames to call the Bullet clusterCluster, '1E 0657-56' and '1E 0657-558'. Furthermore, even Inon the NASA HUBBLE SITEHubble Space Telescope site, they call it, '1E 0657-556'.
I wonder whyWhy is the bullet cluster's name is not the only one?