The coordinates for this episode point to the Pyxis Cluster in the constellation Pyxis. I think a pixie constellation would be rather cool, but that is not what the word "Pyxis" means. Instead, "Pyxis" is supposed to represent a compass, as in a magnetic compass used by sailors and not as in the type of thing used to draw circles. This is another weird constellation invented by the weird eighteenth century astronomer Nicolas Louis de Lacaille to fill blank parts of the sky [1], and of course, it looks like a compass as much as any random collection of dots looks like a compass.
So, let's get back to the Pyxis Cluster. This object, which was, naturally, named after the constellation that it was found in, is a globular cluster. These types of clusters are spheres of old stars that orbit outside the plane of the Milky Way in our galaxy's halo. While a lot of globular clusters have been known about for a century or more, the Pyxis Cluster was only discovered in 1995. Ronald Weinberger discovered this object and a few others using the old-fashioned technique of staring for very long times at photographic plates to try to find interesting things [2], but it took follow-up observations with more modern digital instrumentation to confirm that Weinberger had indeed found an interesting object [3, 4].
The Pyxis Cluster is kind of wimpy for a globular cluster. It has a mass of only 30 thousand times the mass of the Sun (which could be interpreted as meaning that it has approxiomately 30 thousand stars) [5]. Given that globular clusters typically contain up to a million stars, the mass of the Pyxis Cluster seems really small, and this is part of the reason why it was not discovered until 1995.
The other reason the cluster was not discovered until 1995 is that because it is located really really far away from Earth. This is actually what makes the Pyxis Cluster a bit unusual from your everyday average globular cluster. The cluster is located at a distance of 119 thousand light years (36.5 kpc) and at a distance from the center of the galaxy of 126 thousand light years (38.6 kpc) [6]. Its orbit is also very elliptical, bringing the cluster as close as about 98 thousand light years to the center of the Milky Way but then taking it out to a distance of approximately 330 thousand light years [6]. For context, the distance from the Earth to the Large Magellanic Cloud, which is the largest dwarf galaxy orbiting the Milky Way, is 161 thousand light years [7]. So the Pyxis Cluster is basically travelling in its orbit around the Milky Way to distances that are further away than entire dwarf satellite galaxies.
At this point, I tried looking up some sort of technical definition for the difference between a globular cluster and a dwarf galaxy, and it was a bit difficult to find any good discussions about this topic, although it was rather easy to find some rather bad discussions about this topic. One of the more thoughtful discussions was actually listed on reddit [8], although I also found a couple of scientific articles that also try to address the topic [9, 10].
A lot of people would say that one difference between a globular cluster and a dwarf galaxy is its size, but that's kind of lame given that really small dwarf galaxies are equivalent in mass to really large globular clusters. I also read some arguments about the centers of globular clusters being more dense than the centers of dwarf galaxies, but I don't buy that argument, either. However, one argument that I do buy into is that dwarf galaxies contain dark matter whereas globular clusters do not. Another good distinction is that all of the stars within a globular cluster would have formed at the same time and have similar properties, whereas in a very small dwarf galaxy, the stars may have formed at different times and would have different ages. (This all gets extra confusing when considering things very clearly labelled as globular clusters like Omega Centauri that have been identified as once being the centers of dwarf galaxies, but I am going to pretend those objects do not exist for this discussion.)
So, let's go back to the Pyxis Cluster. It's so rinky-dink that if we used the mass criterion, it would qualify as a cluster, even though I don't think this is in general a good way to tell apart globular clusters and dwarf galaxies. Unfortunately, we cannot apply the dark matter criterion because no one has been able to make measurements of the motions of the stars within the cluster that can be used to measure the cluster's mass, which is the best way to identify the presence of dark matter. However, all of the stars in the Pyxis Cluster seem to have formed about 11.5 billion years ago [5], which, using the age of the stars criterion, would point to this object defintiely being a globular cluster and not a really really small dwarf galaxy.
Having said all of that, the Pyxis Cluster's really weird orbit implies that it was once within a larger dwarf galaxy that fell into the Milky Way a very very long time ago [6]. As far as anyone can tell, that dwarf galaxy has been completely absorbed into ours, and it's not possible to see any traces of it aside from the Pyxis Cluster and it's really weird orbit [6].
This cluster is not the first such globular cluster found to have originated in another galaxy, but it and the few other globular clusters like it can tell us about how the Milky Way would have increased in mass over time by absorbing other galaxies. People are therefore going to continue to study the Pyxis Cluster to try to get more insights into the history of the gravitational interactions between the Milky Way and the dwarf galaxies surrounding it.