Collinder 330

A globular cluster lying against a rich region of the Milky Way as it passes through the constellation of Ophiuchus. Collinder 330 is a little over a degree southward of the third-magnitude star Theta Ophiuchi (though at magnitude +9.14, the cluster itself is far too faint to see with the naked eye). Its inclusion within the Collinder Catalogue is unusual, because that catalogue is primarily dedicated to open clusters, and Collinder 330 is one of just eleven globular clusters among the 471 objects listed there.

This is one of a group of globular clusters scattered across southern Ophiuchus, a grouping which also includes M9, M19 and M62. All of these clusters lie between twenty and thirty thousand light years from the Sun, in the general vicinity of the Galaxy's core. For very distant objects like this, detailed dimensions can be difficult to calculate, but the densely packed stars of Collinder 330 appear to be contained within an approximate sphere some forty light years in diameter.