Extra-galactic Globular Clusters

Globular clusters are, as the name suggests, stars clustering together in a roughly spherical ensemble. Each cluster contains between a few tens of thousands and a few million stars. Our Milky Way galaxy has around a couple of hundred of them in orbit around it, which is a fairly typical number for a large spiral galaxy like ours. Some galaxies have very few, if any. Others possess thousands, well over ten thousand in the case of M87, which is a giant elliptical galaxy in the Virgo cluster of galaxies.

Many, many amateur astronomers have published pictures of globular clusters which belong to our galaxy and I've taken a few myself. Here is an example: M2 in Aquarius. Not many people go in search of globular clusters which orbit other galaxies. I started this project through incompetence. Soon after taking over Tacande Observatory, and still learning how to drive everything, I tried to point the telescope at a variable star, AE And in the Andromeda galaxy which is also known as Messier 31 or M31, but missed the target. Rather than discard the image, I examined it to see what it contained — I already knew what was not there. It showed eight globular clusters.

So far I've taken images which show globular clusters around three external galaxies: M31 (as mentioned above), M87 and M81 which is a spiral galaxy in the constellation Ursa Major and one of the closest outside the local group of galaxies.