The object for this episode is the gamma ray burst GRB 020819 in the constellation Grus, which represents a crane (as in the bird and not the mechanical object). The GRB in the name of this object indicate that it's a gamma ray burst, while the digits indicate the date on which the gamma ray burst was detected, which was August 19, 2002. This object sometimes gets labelled GRB 020819B, with the B indicating that it was the second gamma ray burst seen on this date, but, rather strangely, I have been unable to find any information on the existence of a GRB 020819A, so I'll just refer to this episode's object as GRB 020819 and act like no other gamma ray bursts were found on August 19, 2002.
Gamma ray bursts are very brief bursts of gamma rays from explosions in space that could last anywhere from a fraction of a second to a few hours. Two different types of explosions create gamma ray bursts. Bursts shorter than 2 seconds are generally expected to be created when either two neutron stars, two black holes, or a neutron star and a black hole merge, while bursts longer than 2 seconds are expected to be created by supernovae [1]. This means that the progenitor of GRB 020819, which was 20 seconds long [2], was created by a supernova explosion.
People in 2002 had figured out that gamma ray bursts could be associated with afterglows in other parts of the electromagnetic spectrum, and so people went looking for an afterglow associated with GRB 020819 in near-infrared light, but they did not see one [2]. Given this, it was labelled a "dark burst". While "dark burst" sounds like some sort of cool phenomena from science fiction, a Google search quickly reveals that the term is actually more commonly associated with a type of Les Paul guitar [3, 4, 5], although it's also the name of a combo for the dark beam used by Samus in Metroid Prime 2 [6]. Anyway, the reason why no near-infrared light was detected from the dark burst is probably because the supernova that created the burst was embedded within a galaxy with lots of interstellar dust, which can be quite effective at obscuring light in the ultraviolet, visible, and near-infrared parts of the spectrum. However, dust cannot obscure radiowave emission, and in fact radio emission was detected from the gamma ray burst, and the people who detected that radio emission associated it with a galaxy at a distance of 4.4 billion light years [7].
Once the host galaxy of GRB 020819 was identified, people started performing additional observations to understand the nature of the galaxy that hosted this dark burst, partly because "dark burst" is such a cool phrase, and cool phrases like "dark burst" help astronomers get their science proposals approved. Anyway, people determined that the host galaxy indeed contained a lot of dust that obscured not only the gamma ray burst itself but also all of the relatively ordinary stars within the galaxy [8] and that the galaxy contained relatively high amounts of elements heavier than hydrogen and helium [9], which would be the materials that interstellar dust would be made out of.
These results from studying the host galaxy of GRB 020819 went on to define a paradigm for whese these types of dark bursts take place, and astronomers have since used these results from GRB 020819 to understand other dark bursts. Or at least they did until 2017, when follow-up observations using higher resolution observational data determined that the galaxy that everyone had associated with GRB 020819 was in fact a completely unrelated foreground galaxy that was close to but not quite in the part of the sky corresponding to the gamma ray burst and its radio afterglow [10]. The real host of this "dark" gamma ray burst is actually a completely different galaxy with lots of interstellar dust located at a distance where the light has travelled for 10.3 billion years [10] (although, for complex reasons involving cosmology, this does not exactly correspond to a distance of 10.3 billion light years), and I think people are going to need to perform more follow-up observations to understand the newly-identified host galaxy.
So, since the publication of that paper in 2017, I think lots of people have had to unwind their theoretical constructs of where dark bursts are located and develop new paradigms to describe the host galaxies containing these objects. I personally can sometimes find it a bit difficult to change misconceptions of how things work that I have relied on for years, but I do put effort into correcting my misconceptions, and I hope the rest of the astronomical community can do this as well.