Mini Episode 2: Seeing Beyond the Satellites
with Brandon Engelbrecht
Hosted by Bret Yotti
Today we talk with Brandon Engelbrecht, a PhD student from the University of the Western Cape (UWC). Brandon is part of a research group which uses the MeerKAT telescope to study galaxy clusters. These are some of the largest structures in our Universe.
Brandon tells us about his PhD research into improving MeerKAT data by removing radio frequency interference (RFI). This interference can be caused by many different things, including satellites in orbit around the Earth.
Brandon also describes how he went from being a high school student with a budding interest in astronomy, to now working with and improving upon one of the largest radio telescopes in the world.
This week’s guest:
Composite of radio galaxies and MeerKAT telescope: Thousands of galaxies are visible in this radio image covering a square degree of sky near the south celestial pole, made by the MeerKAT radio telescope array (foreground) in the South African Karoo semi-desert. The brightest spots are luminous radio galaxies powered by supermassive black holes. The myriad faint dots are distant galaxies like our own Milky Way, too faint to have been detected before now. Because radio waves travel at the speed of light, this image is a time machine that samples the star formation history of the universe. Credit: SARAO; NRAO/AUI/NSF
This mini-episode was produced and hosted by Bret Yotti from the University of Cape Town.
Bret Yotti (University of Cape Town)
By Bret Yotti
Bret: [00:00:00] Hello, and welcome to this mini-episode of The Cosmic Savannah. I’ll be your guest host today. My name is Bret Yotti. I work at the University of Cape Town where I’m a telescope operator for the teaching telescopes that we have there. Today, I’ll be interviewing Brandon Engelbrecht. He is a first year PhD student at the University of the Western Cape.
At UWC Brandon works in observational cosmology. Cosmology is the study of the origin and the evolution of the universe. Brandon works with MeerKAT data. You might remember MeerKAT from a previous episode of The Cosmic Savannah where it was talked about in great detail. Brandon looks at datasets of large structures in the galaxy, some of the largest structures. He looks at galaxy clusters.
Galaxy clusters are groups of hundreds or thousands of galaxies, which are all gravitationally bound with each other. These are the largest gravitationally bound structures in the universe.
One of the things Brandon is doing in his PhD project is looking for ways to identify radio frequency interference and to remove it from datasets coming from MeerKAT. These RFI sources are usually satellites or other things which emit in the same frequency as the astronomical data that the astronomers are trying to get from the telescope.
Brandon and I first met in 2016 when we were both volunteering for the South African Institute of Physics annual conference, which was held in Cape Town that year, so I was very excited to get the chance to interview him today. Without further ado here he is.
Bret: [00:01:42] Hi, I am here with Brandon Engelbrecht from UWC, and we’re going to talk to him a little bit about why he does what he does. Brandon. Hi.
Brandon: [00:01:52] Hi there Bret, how are you doing?
Bret: [00:01:54] I’m doing great. Thank you. So tell me, what is it that you do exactly at UWC?
Brandon: [00:02:01] That’s a good question, I ask myself that as well. At the moment, I’m a first year PhD student under the supervision of Professor Mario Santos and I’m working on the MeerKAT telescope, which you may have heard of, it’s in the Northern Cape.
What I do at the moment is look at ways of improving data analyzation for our particular project. It’s been a challenging road but so far, I’m enjoying it with mild setbacks here and there.
Bret: [00:02:41] Can you tell me what the MeerKAT telescope is?
Brandon: [00:02:44] It is the world’s most powerful radio telescope. It looks at the sky and looks at sources in the sky, receiving information in terms of light. Then, we get that data back from the telescope. From this, we can see basically what an individual is hoping to find. Many people use the telescope for different things. A few people use it for imaging, a few people use it to map structures in the universe and that’s what I use it for.
These structures are not planets or galaxies, but they’re actually entire galaxies or clusters of galaxies or clusters of clusters. That’s what we use the telescope for.
Bret: [00:03:42] You said that your project has to do with data analysis. Can you tell me what that entails?
Brandon: [00:03:47] At the moment for the PhD, the PhD is the project, but it gets cut up into three sub-projects and each one is as important as the next.
The first one is data analysis of the telescope. We’ve asked the telescope to point at a particular patch of the sky. It then observes that patch and we get data back. My contribution is to analyze mistakes, to actually look for radio frequency interference objects.
These are objects that are man-made satellites. They emit in the same frequency that MeerKAT observes in. What that does to our data, is it completely washes it. It causes a spike in the data that we have to remove so that we can actually get the object that we want to observe. My contribution is basically identifying these RFI sources and finding ways to either avoid them or remove the effects that they have on our data.
Bret: [00:04:57] So does that mean your job is to improve the images that come out of the MeerKAT telescope? To find these sources of noise and find out ways to remove them?
Brandon: [00:05:08] So when we say images, that’s not what we actually look at. We’re looking at temperature maps. You’ll have areas of interest which would be high temperatures, or warm, and areas of no interest would be cold areas. There’s very little galactic activity happening there. The thing with the satellites is because they’re really nearby the Earth and they have this high-power output, they cause flares to be seen in our data. You’d see this at a particular frequency. You’d see an entire bright peak that has no astronomical value to us. It’s just contamination. My job would be to see if the current techniques that we are using to remove them are effective in removing them. Making sure that what’s left behind has very little RFI contamination because we can’t really remove all the RFI contamination, then we would have no data, but can we remove enough to have sufficient data without having severe contamination effects.
The other one is to work on a way to improve avoiding the satellites. If we know where the satellites are, and if we know how much power they’re outputting, then can we point MeerKAT to an area where there are low levels of satellite contamination? Where there are too few satellites or satellites that emit in a different frequency that MeerKAT won’t be so much affected by. That is how I’m trying to improve the data.
Bret: [00:06:54] It sounds like this is a very important job that you’re working on and that it would have a big difference to everybody who uses the MeerKAT telescope, is that right?
Brandon: [00:07:04] I’m not a big picture kind of person. At the moment, I’m just focused on trying to get this project out of the way so I can move on, but my supervisor says the same thing. He says that this is quite important. Those that want to work with the same kind of system that we’re working with on MeerKAT, who get the images and temperature fluctuations. This would be very important for that purpose. My co-supervisor says that SKA would like this software to track satellites, to at least know where and when there would be a cluster of satellites.
Bret: [00:07:44] I’m sure it’s nice to know that you’re contributing to the MeerKAT project and to other future astronomers.
Brandon: [00:07:52] Yeah. At the moment, I don’t see any of this. It’s like this little light at the end of the tunnel that I’m running towards cause right now it’s a doom and gloom kind of thing. Hopefully, at the end of all this, that is where this project can take me.
Bret: [00:08:12] I will stay tuned with your upcoming work over the next couple of years.
Can you tell me, why did you get into astronomy in the first place, and in astronomy, why radio astronomy?
Brandon: [00:08:23] So why astronomy? To be honest, I was lied to. It was false advertising in a sense. In grade 10, I won’t forget this, I watched these documentaries. You have Brian Greene and you have Neil deGrasse Tyson and you have Michio Kaku. They were talking about theoretical physics, and I was kind of going that route. Then I saw Neil deGrasse Tyson, and he introduced me to astronomy, and I was like, “is there a way to combine the two?” And then I found astrophysics. Except nobody told me there would be this high level of mathematics. I knew there would be mathematics, I just didn’t know it would be this high level of mathematics.
So I was just like, “no, what? This is not where I want to go.” But I persevered on. First year, second year, third year. I kind of enjoyed the math a little bit. And then, in Honors, I realized that astrophysics is cool and all that, but I wanted to do something a bit more on a bigger scale. That’s where I found cosmology, which is studying the cosmos but you study objects on much, much bigger scales. We don’t care about galaxies. To us, galaxies are just like a star in the night sky and don’t have so much effect for us. We prefer studying a whole bunch of galaxies together. Even much bigger scales than that. Cosmology had even more mathematics and I was not impressed with my choice.
I pushed some more and then I found out that in cosmology, you have divisions, you have theoretical, which is more math, or you have observational cosmology, which is more like, yes, there’s math, but it’s more computational. It’s more data analysis kind of work. And I was like, “you know what, I’m not prone to the math, but I am prone to working on a computer and writing code”. So then I went and did that one, and from observational cosmology, observational radio cosmology was a very easy choice because of MeerKAT and because they gave me a bursary. So not only did I take their money, I was more obligated to work on work in the radio realm of cosmology. So far, it’s not been so bad because my Honors’ year project, Masters’ year project and now even my PhD project all have similar areas, there’s a connection between each of them.
I’m supposed to know a lot, but I really don’t. I think it’s a problem that most people, outsiders, or people outside of academia think we know a lot. Honestly, there are people that do, and then there are people like me that no, not really. I’m just here trying to get project one out of the way so I can move on to project two. But, it’s a different ball game when you’re having to work with these supervisors and professors and stuff. It’s just very, very intimidating.
Bret: [00:11:34] So just to get this right, you fell in love with astronomy in high school, then got to university and were turned off by the math, so you rethought about it and thought, “okay, I’ll choose cosmology”, which I believe is the most math-heavy field of astronomy. If I’m not mistaken?
Brandon: [00:11:52] That’s correct, yes.
Bret: [00:11:54] And then you found out, “oh, more math, so I’ll choose radio astronomy or observational cosmology”. Then you chose the most math heavy observational method of astronomy as well. Is that right?
Brandon: [00:12:07] So I chose a more computational and data analysis side. I was trying to avoid going deeper and deeper into this mathematical realm of cosmology. I was like, “this is the point where I am turning, to this side of the world”. So yes, there’s still a lot of math that I have to do and stuff, but at least I don’t want to rack my brains on pages and pages of equations, which might sound like I ran away. But honestly, I did run away.
Bret: [00:12:37] You just ran to the coding side.
Brandon: [00:12:40] Yeah. I ran to the coding side for a few reasons, one of which is I do want to improve coding skills. Two, coding is the future. Three, if astronomy or cosmology doesn’t work out, I can always try my skills in the real world of, all astronomers go into this now, data science.
Bret: [00:13:02] So you can always fall back and find a job in the business sector, I think, right? With your coding and your data science skills that you’ve learned.
Brandon: [00:13:09] Yes.
Bret: [00:13:12] Thank you for your time, Brandon. It’s been great chatting with you.
Brandon: [00:13:17] You too Bret.
Bret: [00:13:24] Wow. What a great chat that was with Brandon. I especially liked his story about his road. Where he started with an interest in physics, went to astrophysics and then changed to cosmology and then changed to this observational radio cosmology. And throughout it all, he didn’t let that heavy math deter him at all.
It really sets an example for future astronomers to persevere. Now Brandon is working with one of the biggest radio telescopes in the world, and not only that, but he’s making it better for future astronomers who use it. And this work is only going to get more and more important moving forward as companies like SpaceX keep launching satellites. SpaceX, for example, has over 540 of these Starlink satellites that have gone up just in a little over a year and have plans to launch over 12,000, so this work Brandon is doing is going to be more and more important moving forward.
I just want to thank Brandon again for chatting with me today and thank you for everybody who tuned in and I hope to speak to you again in the future.