Black holes, still something of a mysterious stellar object, generally come in to flavours - a little bigger than our Sun, all the way to way, way, more massive than our sun (a few billion times, in fact)

However, a Sydney Uni team discoverd the first middleweight black hole back in 2009, and now have been a part of the team that has grabbed the first radio emissions from the hole as it changed phased between emitting lower and higher energy X-rays.

"Black holes change state from a low luminosity X-ray state to a high luminosity X-ray state, and back again. As they change state they release jets of superfast moving plasma which can be measured by the radio waves emitted," said Dr Seam Farrell, the Australian lead researcher on the project, in a press release.

The measurements, made using the Compact Array and NASA's Swift satellite, found that the intermediate black hole being monitored, designated HLX-1 and positioned about 300 million light years away, emitted these radio emissions in a very similar way to other black holes when they change state.

Using these radio emissions, the team was also able to make a better prediction about the black hole's size.

"From the radio emissions released by our intermediate mass black hole HLX-1, we can also calculate its approximate size. So we've been able to refine our estimate of how big HLX-1 is to between around 9 x 103 times the size of our sun and 9 x 104 times the size of our sun," said Dr Farrell.

"It's further proof that HLX-1 is indeed sized as an intermediate mass black hole."