Episode 25: A Year in Review

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In this the final Episode of Season 2 of The Cosmic Savannah Podcast, Dan and Jacinta look back on the past year, and some of their favourite episodes.

Amidst the Coronavirus pandemic, we look at how astronomy is contributing to the building of ventilators as part of the National Ventilator Project.

We also look forward to the year ahead and some of the exciting events to look forward to in 2020/21.

We highlight just some of our favourite episodes including our very first on Near-Earth Asteroids with Dr Moses Mogotsi and Dr Nicolas Erasmus. It featured the new ATLAS (Asteroid Terrestrial-impact Last Alert System) telescope soon to be housed in Sutherland.

Another big favourite was the announcement of the Event Horizon Telescope’s first-ever image of a black hole where we were joined by Prof Roger Deane! We also talked about how Africa will be contributing in future.

We also look back on a stargazing trip under African Skies with Dr Tanya Edwards and Dr Simon Bihr

For these and all of our past episodes you can visit:

Finally, we talk about some of the things to look forward to over the next year, like the launch of the James Webb Space Telescope, a new Mars Rover, and many more Gravitational Waves!

The magnificent James Webb Space Telescope
Recording under lockdown

We hope you’ve enjoyed listening to this past year and we look forward to joining you again for more awesome African Astronomy!


Jacinta: [00:00:00] Welcome to The Cosmic Savannah with Dr Jacinta Delhaize

Dan: [00:00:08] and Dr. Daniel Cunnama. Each episode, we’ll be giving you a behind the scenes look at the world class astronomy and astrophysics happening and Africans skies.

Jacinta: [00:00:17] Let us introduce you to the people involved. The technology we use, the exciting work we do, and the fascinating discoveries we make.

Dan: [00:00:24] Sit back and relax as we take you on a safari through the skies.

Jacinta: [00:00:31] Welcome to episode 25 everyone. It’s the last of season two

Dan: [00:00:36] and our one year anniversary.

Jacinta: [00:00:38] Yeah. We actually missed our one year anniversary. We forgot

Dan: [00:00:43] as long as we both did it’s ok.

Jacinta: [00:00:46] Yeah. haha right.

March 31st was one year since the day we launched The Cosmic Savannah. And what a ride.

Dan: [00:00:54] Yeah, 25 episodes so we’ve averaged one every two weeks then.

Jacinta: [00:00:59] Yeah, 25 episodes. It’s pretty good.

So I hope you’ve all been enjoying it. And in this episode we are just going to have a chat and reminisce about our favorite moments over the past year and have a chat about what’s happening in astronomy here at the moment and what is going to happen in the next year. Hopefully.

Dan: [00:01:21] Yeah, and obviously as you can hear, we’re recording over Skype again, because of the lockdown and covid outbreak.

But one of the really cool thing, one of the astronomy stories, well, astronomy related stories that came out in this last week, which I don’t know if many people have seen, is that the South African Radio Astronomy Observatory, who we talk about quite frequently. They run the MeerKAT radio telescope, which is a proudly South African project in South Africa, and they have been appointed to manage the development and production of 10,000 ventilators by the end of June. So they’re running the national ventilator project and obviously using all of their engineering skills and experience making world class technology and innovative development to do something to help this crisis. Which is pretty, pretty cool.

Jacinta: [00:02:14] Yeah. I think that’s fantastic.

I was reading the article you sent. I loved the quote. One of the astronomers said, if we have the skills that put the MeerKAT together. Why can’t you use them to put together a medical capacity? And I thought that was fantastic.

Dan: [00:02:30] They’re not just running it themselves. They are getting input from companies who are volunteering their services around the country and to provide a hundred percent local parts because obviously parts for ventilators at the moment are in dire need across the world.

And there’s a lot of competition for these parts. So to create these things from locally manufactured products is really going to be quite exciting. And as I said, we have about 6,000 operational ventilators in the country at the moment. But we’re going to need a lot more than that. And the plan is to produce 10,000 of these things by the end of June.

And beyond that, possibly many, many more. Very, very cool. And people often ask us, what’s the point of astronomy? This is, this is a wonderful point of astronomy. We can be very, very proud of the skills we’ve developed as the human capacity we’ve developed in producing the Meerkat telescope. Which are now getting directly used for something which is incredibly important to the country right now.

Jacinta: [00:03:28] The people who work for SARAO have a whole range of skills, from large scale project management with lots of complicated parts to engineering expertise, design expertise, the whole, the whole range. It’s so great that it can be applied in this case.

Dan: [00:03:45] Alright. Right. So exciting news to start us off.

Jacinta: [00:03:47] Yeah.

Dan: [00:03:49] So we’ve put together a list of some of our favorite episodes from the last year and season.

Jacinta: [00:03:55] Well, I put a list together of mine, but I don’t see any of yours on there, or unless you have the same ones as me.

Dan: [00:04:01] I think some of them are the same, not all of them. Certainly. The first one on the, on the list was our first episode on near earth asteroids.

Which is still one of my favorites. I think it was very, very cool. People love talking about asteroids. I love talking about asteroid.

Jacinta: [00:04:15] Yeah, and asteroids that can hit the Earth.

Dan: [00:04:17] It’s actually a big asteroid coming past on the 29th of April. I’ve had a couple of queries about it. Oh, really? Are we all going to die.

The answer as usual is no,

It’s a big one. It’s, it’s over a kilometer across. But it’s gonna. It’s gonna miss us by 16 times the distance to the moon. It’ll be a cool thing to observe, and there’ll be definitely be telescopes trained on it as it comes past, but near asteroids. Yay.

Jacinta: [00:04:47] Yeah, that’s super cool. And so back at the start of 2019 when we talked to Nick Erasmus in episode one, he said that ATLAS was going to be built in Sutherland.

So are there any updates on that?

Dan: [00:04:58] Yeah, absolutely. Uh, I saw just this week that the concrete has been laid, the foundation has been laid for the telescope and we are expecting the dome in the next month or so, and then the telescope will arrive before the end up the year. So just to remind our listeners that ATLAS stands for asteroid terrestrial impact last alert system.

There are currently ATLAS telescopes in Hawaii, which monitor any small asteroids. From about two meters up to about a hundred meters, which are going to impact the earth on a time scale of up to two weeks. So less than two. So it’s, it is a real last alert system. It’s just picking up the things which are coming in very, very fast and are likely to hit us.

And we will be getting one of those in Sutherland at the SAAO by the end of the year and then we will be covering the Southern hemisphere, which is not being covered up until now. And once that’s installed. The ATLAS telescopes will basically have full 360 degree coverage of the skie, and we can see these kind of things coming.

Jacinta: [00:06:04] Yeah, we can see them coming from anywhere now. That’s very exciting. Cool.

Dan: [00:06:09] Oh, that’s very cool. And obviously as that project progresses we’ll speak to Nick again and some of the other people involved. I’m sure some very exciting science is going to come out of it too.

Jacinta: [00:06:18] Yeah. Can’t wait. I might cut in some snippets from these episodes.

So listeners, you may in a moment be able to hear some of Nick Erasmus speaking about the asteroids, but as we’re recording, I don’t know what we’re going to do.

Nick: [00:06:33] Currently, ATLAS consists of two telescopes that are situated in Hawaii, and they scan the sky every night to discover new asteroids.

The problem with only having them in Hawaii is that you can mainly only cover the Northern hemisphere. So ideally you want to put these telescopes all over the globe, North and South, and also different latitudes so that you can cover 24 hours a day. And South Africa has been earmarked to get one of these because we are pretty much exactly opposite to Hawaii in terms of North South and also we have exactly 12 hours time difference. So South Africa is the ideal place to have another one of these telescopes to, to have full coverage. These asteroids when they come close to us can become super bright. We’re really looking at the ones that are just about to hit us. So the ones that are coming really close to us.

ATLAS is supposed to catch those. To give  you an idea ATLAS is designed so that it can detect a hundred meter diameter asteroid with a three weeks warning notice and a ten metre diameter asteroid with two days notice.

Jacinta: [00:07:33] Another of my favorite episodes was, again, back in the beginning, episode three, when I spoke to Dr. Griffin Foster about doing SETI searches with MeerKAT. So searching for extraterrestrial intelligence, which I didn’t realize was actually a dedicated thing happening with MeerKAT

Dan: [00:07:50] yeah. That’s very cool. Everyone loves aliens. Or at least the thought of aliens. You know, you have this, the most powerful radio telescope in the world now.

It’s something that people have dreamed of being able to get hold of. Jodie Foster had had the last one in contact, the VLA and the dream is to be able to pick up alien civilizations or alien contact through one of these big radio telescopes. Whether we do that or not with MeerKAT remains to be seen.

Um, I’m not convinced, but I do think it’s a very, very cool thing to be investigating. And we have all the data. It’s all streaming through, so we might as well take a look.

Jacinta: [00:08:25] Yeah, it’s called the Breakthrough Listen project, and it just piggybacks on the rest of the observation. So there’s hardly any time, I think, dedicated actually towards that.

So it doesn’t really take away any other science time, but it’s still looking through all of the data. And you might as well, you might as well look.

Dan: [00:08:41] So did you, I mean, again, there’s so much data, more data than the astronomers know what to do with right now. So anybody who’s prepared to look at it for any sort of signal, whether it’s from extraterrestrial intelligence or not, they may discover something very interesting.

Griffin: [00:08:56] And over this last decade, last 20 years, it’s been this boom, and we now know that there’s planets everywhere. Most star systems have a planet, if not many planets. And the fact that we know this now is kind of an exciting thing. This idea that of course there’s so many planets. I mean, it seems so obvious now, but we now have this evidence and an obvious question next is, what’s on these planets?

Do they have atmospheres and do they also have life? And people are, are kind of moving from finding planets to now figuring out what these planets are made up of.

And this is a really great moment because at the same time, this kind of brings. Forward, the idea of doing SETI again, I think this discovery of exoplanets has really boosted the interest in SETI again. Three years ago, this kind of interest built to a really phenomenal event.

The breakthrough initiatives, which is this organizationfounded by some fairly interested people, but also fairly rich people. They wanted to fund science to look for life beyond earth in a number of ways. And the initial project is called Breakthrough Listen and Breakthrough Listen is a project.

It’s funded over 10 years. It’s been going for three years now to use radio telescopes to look for signatures of advanced life on other planets.

Jacinta: [00:10:12] Have there been any updates from Breakthrough Listen, do you have any updates?

Dan: [00:10:15] Not as far as I’m aware. I don’t have any personal updates and I know that Breakthrough are supposed to be having a meeting here in South Africa in October, but I imagine that that’s probably going to be canceled or postponed in light of the current situation.

Jacinta: [00:10:31] I guess a lot of things will have to be postponed.

Dan: [00:10:35] The next one on your list, and definitely one of my favorites was episode five the Event Horizon Telescope where we spoke to Dr. Roger Dean, Professor Roger Dean.

Jacinta: [00:10:44] He’s a professor now.

Dan: [00:10:46] That was a, obviously an incredible event, the unveiling almost a year ago to the day of the first ever image of a black hole or the material just around the black hole.

And that image I think has been seen, it was insane, by like four and a half billion people in the world or something. Uh, some more than half the world’s population have seen that image now. Very, very exciting astrophysical event, something which is, you know, it doesn’t get much bigger than that. And yeah, we were very fortunate to speak to Roger about his role in it and South Africa’s role in it himself and his students.

And he explained to us how it all worked and how they managed to achieve this incredible thing.

Roger: [00:11:27] The image that was made. It was a, it was a complete ring, which is basically what we call the shadow of the black hole. But what we were seeing is light in the immediate vicinity of that boundary layer, which defines the point of no return when you enter the black hole and exit our universe.

There’s a sharp feature at this boundary point. So there is a point at which light disappears from the universe, if you will, or at least from our view of it and that which does come to our telescope and eyes. And that is a sharp feature known as the black hole shadow. On cosmic scales this is a fairly nearby giant, what we call elliptical about 55 million light years away.

And essentially at the center of this gargantuan galaxy lies a very, very massive black hole. And that was the image that we unveiled yesterday.

Jacinta: [00:12:19] Yeah. It was such a privilege to be able to put out an episode on this and to already have a podcast so that we could talk about it, because really it was a once in a lifetime thing to be around for something that big to be announced.

And we also spoke to Dr Rhodri Evans in that episode, who was speaking about the plans to build the African millimeter telescope, the AMT in Namibia. And how that will be incorporated into this whole event horizon telescope, hopefully to enable it to hopefully image the black hole at the center of the Milky way, Sagittarius A*

Dan: [00:12:55] yeah I think that in the next year, well, hopefully in the next year or two, we’ll definitely be seeing more coming out of the event horizon telescope. I think it was a very successful project and as you say, we don’t have an image of our black hole, Sagittarius A*. Well, let’s hope we get one soon.

Jacinta: [00:13:12] Yeah. Actually, you and I were were tricked by an April fool’s joke this year weren’t we? Hook line  and sinker.


Dan: [00:13:21] re-posted the media advisory. That there is going to be an announcement from the EHT, and I was convinced that they were going to announce the Sagittarius A*. Only to realize that the announcement was on the 10th of April, 2019, not on the 10th of April 2020


Jacinta: [00:13:40] I already contacted Roger to ask for another interview about it, and he said, Oh, I think you’ve been tricked.

Dan: [00:13:47] That’s some solid reporting by us

Jacinta: [00:13:53] And that’s why we need to follow up on our sources. On a completely different note, I loved episode seven when we spoke to Dr Tonya Edwards and Dr. Simon Bihr who had just taken an incredible journey riding their bicycles from Germany all the way to Cape Town through Africa.

Uh, and they told us all about the incredible things that they saw. Ah, the animals, their experiences, the people, the night skies that they saw with pristine, dark skies of Africa, which again, and again we keep saying is, is such an amazing commodity that Africa has. And Tanya was also telling us about her work using the gamma-ray telescope, HESS in Namibia.

Simon: [00:14:37] We had, I think two highlights about the stars and the sky. The first was the Sahara desert in Sudan. There is just no one around you. You have like three, 400 kilometers of nothing than just sand. So the sky is extremely dark. We were fortunate at that point it was also a new moon, so we had no moon in the way.

And then you can just see… It feels like billions of stars. It was fantastic. You see the Milky way all the way to the horizon, and we even saw the zodiacal light, which is something I’ve never seen before.

Tanya: [00:15:13] In Namibia was I would say was the next best sky that we saw. Namibia is a lot of desert and yeah, very few villages and the sky was incredible, actually, so incredible that sometimes it was hard to distinguish the Milky Way from the rest of the sky because there were just so much light around, so many stars around.

I probably saw more of the night sky cycling through Namibia. Professionally, when you’re there, you’re obviously working at night, you’re doing a lot of long shifts. Of course, that’s why you’re there. But we could just camp in the middle of nowhere in the desert. We didn’t have to be close to any facilities or any big roads. We took very small roads through an Namibia. So I would say probably cycling, we saw a much more.

Dan: [00:15:56] Yeah, I mean, that was a, that was a very nice episode. Nice to take a step into the beauty and the awe that astronomy inspires and celebrate the African skies. Another one of my favorites, which I’ll go into straight away, is episode 14 where we visited Kruger, the Kruger national park in South Africa.

That was obviously very, very special. Being able to see the game. We went on game drives, see the stars and the national park like that. And just spend a few days talking about astronomy in such an incredible location, obviously I’m South African, and I love Africa and the Kruger and everything that goes with it, but it really is a very exciting thing.

And being involved in astronomy and being able to explore those incredible places it’s really quite special

Jacinta: [00:16:44] As a non South African, as an Australian, it was my first experience going on, well, we call it safari, but the correct term is game drive. I don’t want to show my foreignness too much.

I was so excited to see all of the animals and yeah, as you said, we got to watch the sunset over the savannah and watch all the stars come out and the moon. And it was breathtaking.

So night is starting to set in on the savannah,

Dan: [00:17:13] We’ve turned down the lights. We have big game lights to scan the bush for eyes so that we can try and find which animal owns those eyes.

Jacinta: [00:17:23] We saw quite a spectacular sunset. It was very red.

Dan: [00:17:26] It was beautiful. So now we’re looking for the nocturnal animals. There’s like a day-night switch where the whole different group of animals come out at night. They live in the dark and hunt in the dark, and we’re looking for those. No.

Jacinta: [00:17:39] Wow. We’ve just turned off the lights and the moon is rising.

And it’s orange, bright orange. Incredibly beautiful. This is the real cosmic savannah hey Dan?

 Also in that episode, Dan. It was all about a conference that you have put together and I must say you did an excellent job and we were talking about simulations, which we don’t get to speak about that much, even though it’s your field.

We very much biased towards observational astronomy, but yeah, we got to spend the whole episode talking about the simulations of galaxies that are being produced at the moment and really cutting edge stuff.

Dan: [00:18:16] Yeah, it’s obviously my field and we spoke about it a little bit in episodes eight and nine.

Talking about simulations with my previous supervisor Romeel who obviously co-organised us the conference with me. We should definitely catch up with Romeel and some other simulators about what’s going on in that field. And maybe next year we can have another conference.

Jacinta: [00:18:37] Well, I wouldn’t mind. Since we’re talking about going on excursions.

I also took The Cosmic Savannah on a, on an excursion to Australia in episode 11 and 12. I was there for a conference about HI – neutral hydrogen gas, which is what I work a lot in. So of course those were a couple of my favorite episodes because I got to introduce the listeners to Australia and the exciting work going on there and how there’s so many collaborations between Australia and South Africa, both technically with the building of the SKA in both countries and also scientifically. We collaborate so much with each other, particularly in my field of, HI astronomy, and it’s developing so rapidly this field right now with all of the data being pumped out of MeerKAT and Australia’s ASKAP telescopes. Papers are flying out the door, which is very exciting, and we’re detecting, we’re detecting neutral hydrogen gas in galaxies out to much further distances than we previously have in larger quantities, so I won’t say too much more because many of the papers haven’t been published yet, but we hope that we can talk about it more in the next season.

Dan: [00:19:45] The next one on your list here you have is episode 13 where we focused on my place of work at the South African Astronomical Observatory and all of the things going on here and spoke to my boss, Professor Petri Vaisanen. It’s something obviously very close to me. It’s kind of hard to look at it from an outside perspective.


Jacinta: [00:20:04] you’re being too coy. I mean, it was actually one of our most popular episodes ever. It was amazing to hear from the director of the South African Astronomical Observatory, Petri. And he told us all about his plans for the future of the SAAO. And there’s some really cool futuristic sounding things in there. An intelligent observatory, robotic telescopes, AI deciding what these telescopes are going to look at and when and, and SALT 2.0

Dan: [00:20:35] I guess, some pretty exciting things happening.

Petri: [00:20:42] At the moment, we’re in the stage of essentially doing a three year pilot project, changing a subset of our own telescopes in Sutherland to be flexible. So some of them still need human intervention to change instruments, for example. And we need to get away from that.

SALT already does. It takes 15 seconds to go from spectroscopy to imaging. Just a click of a button on the monitor, but some of the other telescopes don’t do that. You actually need a team of people to come in the afternoon to change the instruments. So we need those changes to be automatic, remote so that you can do it from anywhere, making them remote observable from Cape town, which already happens partially.

And then lots of intelligence and software development. I know it’s a buzz word, and you know, politicians use it for, for their own purposes, but it does remain true that all of this connects very well with what’s called the fourth industrial revolution and whatever it means in practice. The whole concept fits so well with what countries like South Africa want to do in the future.

Raise the level of hi-tech. Raise the level of how do you do technology, merge human-machine, human-algorithm interfaces. It’s, it’s an exciting application of these kinds of projects. Studying space, studying the universe, studying how the universe really deep down works in the framework of this could be a fourth industrial revolution type of a project.

Dan: [00:21:57] I should also mentioned that I’m busy building a visitor’s centre here in Cape Town. So hopefully by October we will have a world class visitors centre with some exciting exhibits so that they can display some of this science and technology that we are using.

Jacinta: [00:22:10] Yeah. And I’ve seen some of your plans and it’s looking really, really cool. You’ve put in a huge amount of work on that, so I’m really looking forward to seeing that manifest in real life.

And then we can have people come and visit the visitor center, check out the stuff we’re doing.

Dan: [00:22:25] Yeah. That’s very exciting.

Jacinta: [00:22:26] Another very popular, actually, our most popular episode to date was episode 19 which was about the Molo Mhlaba which is being run in the Khayelitsha community. And we spoke to Honey Phali and Dr Margherita Molaro who are running that project. They won a prize for their efforts and Honey got to go on a trip to Japan, to a conference there run by the international astronomical union where she presented the project and learned a lot about how other people around the world are helping with education in astronomy and inclusivity. And things like this. She seemed to come back with a lot of amazing fresh ideas. It was also really awesome to chat with the small girls who are participating in the program and hear their enthusiasm and hear their singing and watch a concert by them.

So I had a lot of fun with that episode.

Dan: [00:23:23] Yeah, it was very cool episode and it’s an amazing project, as you said, some very impressive work and something which I hope continues long, long into the future.

Jacinta: [00:23:32] That was also the first episode where we have included some translations into Xhosa and Sesotho. We haven’t managed to do any further episodes in different languages yet, but that is certainly a plan for the future.

So I thought that was also really cool.

Honey: [00:23:49] So historically, the face of science has always been a man, and it has always been white. So we are trying to change the face of the science and where science is made. When we started with Thope foundation  we wanted our girls is to have confidence, to see science, to see the application of science in their day to day lives.

Because you know the perception with science and mathematics, it’s always that it’s a difficult subject and you must only be in like town schools to be aceing in the subject. And it’s not, it’s not the truth. So we wanted to inspire those girls and mentor them to participate in science.

And we’re doing that. And in astronomy, because Africa’s booming in astronomy. So we went to place as many girls, motivate them, encourage them, in the field of astronomy, that’s our mission. And also in addressing the challenges that we have in South Africa. The high femicide. And you know, South Africa is not a safe country.

So going to Tokyo to experience a country where there’s so much peace. There’s safety, it gave me hope and I came back with like a different perspective and I’m someone who would believe that it’s probably politics that would change our country, but it’s actually not. No amount of politics would change that.

It’s us citizens of South Africa being patriotic about our country and saying we love it. We’re going to take care of it.

Dan: [00:25:26] Another great episode I thought was the interview with Dr Fernando Camilo, who is the MeerKAT chief scientist. Now MeerKAT has been operational for going on two years now, and there’s a lot of data that’s being collected.

A lot of it’s been handed to the scientists who have run a lot of analysis and are now starting to push out papers and publish the discoveries, which is very exciting. That one of the first ones was the one we featured in episode 22 which was the discovery of these enormous bubble-like structures that go on for hundreds of light years.

Above and below the Milky way, the disk of the Milky Way, getting blown out by the center of the galaxy. Some very, very cool discoveries. Some cool images too. That went along with it and just a, a great example of the incredible science, which is going to be coming out of out of MeerKAT and Fernando spoke to us about that, that particular discovery, but then also the incredible achievement that is MeerKAT.

How it came to be and the incredible discoveries which he sees coming out of it in the next decade.

Jacinta: [00:26:32] And these super bubbles coming from the center of the Milky Way, were the first example of an unknown unknown that MeerKAT discovered. So Meerkat was obviously built for certain science purposes, as a very powerful radio telescope.

But one of the most exciting things you can do with these new instruments is just turn them on and look at the sky and see what you see. And there’s probably going to be things there that you didn’t plan to see. You didn’t build it to see because you didn’t know they were there. And that’s why we call them unknown unknowns.

And we didn’t know these bubbles existed, and then MeerKAT found them. And that was really momentous and it was one of the first things that it did. So the future is looking really positive in terms of what else we’ll find out there.

Dan: [00:27:13] Yeah, absolutely. And which leads us basically into episode 23 which was also about MeerKAT.

Some of the exciting discoveries coming out of that where we spoke to Professor Patrick Woudt, who is the head of astronomy at the University of Cape Town and his project Thunderkat where they are also using MeerKAT to look for transient events, so things that are happening either on very short scales or varying over time, and they’ve recently observed a black hole objecting material and close to the speed of light. Again, making a very, very large ejection of material across the sky. Just another incredible discovery coming out of MeerKAT. And I think that we are going to be inundated with such discoverie in the next few years.

Jacinta: [00:28:00] Patrick also spoke about the fact that this year is the 50th anniversary of the department of astronomy at the University of Cape Town, and it’s also the 200th anniversary of the South African Astronomical Observatory – SAAO. And you are heading up the celebrations for that, Dan. Now, of course, everything has been suspended for a while due to the Corona virus outbreak.

Are there any updates on your end for that?

Dan: [00:28:24] Yeah, so at the moment, I’ve been having many, many meetings about contingency plans for the events that were due to occur in October. We had planned the launch of the visitors center, which I alluded to earlier, and that will still go ahead. Because we can still continue construction and things, but in terms of having a large astronomy festival and getting thousands of people in one location, that seems very unlikely in October, the same goes for the big astronomy symposium, which we were planning to hold.

So those events are most likely going to be delayed. And we are targeting two dates, potentially either March next year or October 2021 so we may have to delay by a full year. Obviously we don’t really know what’s going to happen with the pandemic and how it’s going to evolve. So we’re keeping close tabs on that and trying to plan as much as we can around that so that we can continue with these events and still hold a successful celebration.

Jacinta: [00:29:20] Of course it’s a shame and we’re sad that it has to be suspended like this, but we are also very thankful and grateful that we are all safe at the moment, and we know that it comes first. People’s safety and health, and we want to make sure that that’s the absolute top priority.

Dan: [00:29:38] Yeah, no, for sure. And you know, astronomy will always be there.

Jacinta: [00:29:42] The stars aren’t going anywhere. Unless a few of them go supernova in the meantime,

Dan: [00:29:48] and some of them just zip across the sky. But you know, let’s not get into specifics.

Jacinta: [00:29:55] Well, there are transients. That’s what Patrick was talking about in episode 23 things that suddenly go bang and then don’t do it again.

But I think there’ll be more opportunities for us to find them. So in this, in this lockdown, SALT has also been suspended. It’s operations. And we don’t know when that will go ahead. But do you know of any recent advances with SALT? So

Dan: [00:30:17] there’s a couple of things with SALT. The SALT has always been remotely operable.

And that will continue. At the moment we did shut down primarily because  we weren’t planning to have anyone on the site in Sutherland, and so that shut down will go on for as long as the lockdown does, and we can get people back to Sutherland, then we can continue remote operations as we need and sort of keep the number of people there to a minimum.

In terms of science and technology advances, we do have funding, which is currently on a three year scale to build new instruments for SALT. So we’re building one new instrument for SALT called MAX-E, which will be a highly efficient spectrometre. And that’s in design phase at the moment and doing a critical design review and yup, that should be online in a couple of years’ time.

Jacinta: [00:31:05] very cool. I think Petri did mention that in episode 13 as well. I think, look, all of the episodes I’ve really enjoyed, it was hard to pick a few, but those are our personal favorites. So during our hiatus, if you are bored and you, you want your fix of The Cosmic Savannah, we salute you. And these are the ones that you can maybe go back and check out.

So now onto things to look forward to. In 2020/2021 what are our plans, Dan, for new episodes? I’ve got one in mind.

Dan: [00:31:36] Well, obviously I mentioned earlier, ATLAS is, that’s a very, very exciting thing for me and for the observatory. It’s an amazing telescope funded by NASA, hosted by us. It’s a great collaboration and it’s, it’s going to discover some really cool stuff on very short timescales, which is going to be exciting.

Getting a notification that this thing’s coming and it’s going to be here in eight hours, you know, that kind of stuff is going to be very, very cool. I’m looking forward to that coming online and we will sit and talk about that more. A couple of other things. The big one for me, for a year’s time now, which seems very hard to believe because of the, the amount of delays it’s undergone is the launch of the James Webb Space Telescope.

Jacinta: [00:32:16] Yeah. This has been delayed for years and years and years, and we’re all very excited about it and Oh, it would be so great if it actually launches next year.

Dan: [00:32:27] Yeah, so it’s scheduled to launch on the 30th of March, 2021 we actually spoke about Hubble and James Webb in episode 17 about that, you know, everyone loves the space telescope.

Hubble is like the world’s favorite telescope and James Webb is going to be so much bigger and more exciting than Hubble. It’s going to have a slightly different science case and looking at slightly different things, but in terms of astronomy projects and things coming, it’s definitely one of the most exciting things on the horizon.

Jacinta: [00:32:59] Yeah. I think I mentioned also on, on episode 17 that I actually got to see the James Webb Space Telescope being constructed when I visited NASA Goddard in 2016 and the big solar panels were open, which are golden, and it was facing me, and it was just so breathtaking and how reflective they are. So yeah, really, really cool to see this Hubble 2.0 launched.

And we’re looking forward to even more and more and more gravitational waves being detected. LIGO is absolutely pumping them out. There’s 67 gravitational waves that have now being detected as of early 2015 they had never been detected ever before. And then finally one was detected back then, and since then, just more and more and more have been pouring in. LIGO the, oh gosh, what does it stand for Dan?

Dan: [00:33:50] Laser interferometer gravitational wave observatory.

Jacinta: [00:33:55] That would be my guess as well. That is now in stage three of operations and since then has really ramped up the number of detections. We haven’t actually done an episode on gravitational waves yet. Dan, we must fix that.

Dan: [00:34:08] No, we must fix that. We did speak about it with Petri, abut SALT’s involvements in the neutron star merger.

But yeah, we should do a dedicated episode on gravitational wave astronomy.

Jacinta: [00:34:19] Yeah. You’ve been saying that ever since we started the podcast, so we really need to get onto that.

Dan: [00:34:23] Okay. Episode one. Season three.

The other thing I thought was pretty cool though, it’s not directly astronomy, it’s just space, is that NASA is sending up their next Mars rover in July this year and they are on track for a July launch and that rover, which is following in the line of Spirit and Opportunity and

Jacinta: [00:34:45] Curiosity,

Dan: [00:34:46] Curiosity. Is called perseverance.

And yeah, it’ll be going up and a brand new Rover on Mars. The other ones have done a long time and done very, very well. But you know, these things on mars always discover some cool stuff, and I think that, I just think landing rovers on another planet is super cool

Jacinta: [00:35:04] it’s epically cool. I want to watch it.

Oh, it will be so exciting. Yeah,

Dan: [00:35:10] And especially how they land them

Jacinta: [00:35:12] yeah, exactly.

The parachute.

Dan: [00:35:15] Yeah, there was a time when they landed on the full and rolled around and they opened up like, they don’t do that anymore. Now it’s like this thing comes in and it’s got a heat shield and then it’s got a parachute, and then it’s got like this, like helicopter thing, which it’s not a helicopter, but it’s got jets.

Jacinta: [00:35:32] It’s like a jets and they’re like, yeah, it like balances itself and then it lowers itself down.

Dan: [00:35:37] Like a sky crane. Yeah. It’s like this thing flies in at thousands of kilometers a second or thousands of kilometers an hour and then stops two meters above the ground. Which is just insane. And then it lowers the rover down on a crane. Like, argh!

Jacinta: [00:35:57] Well, we’ll be watching for sure when that happens. Have you, have you ever seen the curiosity rover’s unofficial  Twitter account Sarcastic Rover? I’m such a fan. It’s hilarious. And it really, it gives you a different, a different perspective on, um, on life, on Mars

Dan: [00:36:21] and the loneliness

Jacinta: [00:36:22] and well, it’s relevant because we’re all in isolation at the moment. So maybe we can take a few lessons on how Curiosity is dealing with it out there. But anyway, I think we should maybe wrap it up for this episode and this season.

Dan: [00:36:36] Yeah, I think it’s been a very successful last season last year, and we look forward to the next one.

Jacinta: [00:36:42] Yeah, and I think we just want to really thank you all for listening, all of our listeners for your feedback, for your comments and reviews. We really, really appreciate it. Feel free to keep getting in touch with us on social media or by our website contact page. We love hearing from you and in the time during our hiatus we will be training up some astronomy students who would like to help volunteer with The Cosmic Savannah. We’re going to teach them some podcasting skills, and they might even be creating their own mini episodes, which depending on how it all works out, we might be able to publish here on The Cosmic Savannah during the hiatus to give you something to listen to.

And the other thing that we’re doing is trying to work through creating the transcriptions of all of the episodes so that you can read along as you’re listening. This is to improve accessibility. So you can go to the show notes of each of our episodes on our website to read along.

 And in that respect. I’d also like to give a big shout out to our dedicated team of volunteer regular transcribers, which includes Sumari Hattingh, Brandon Endelbrecht, Lynette Delhaize, who is my mum. Hi mum! And also recently joining the team is Alison Munn, who has a lot of professional experience in transcribing and has kindly volunteered her time to us.

So thank you very much. And also thank you to the UCT astronomy department for coming on board with sponsorship and they are paying for part of the software that we use for the editing and the transcription. So thank you very much for that.

Dan: [00:38:18] And if you’re looking for some other astronomy related podcasts to keep you busy while we’re on hiatus, we can definitely recommend a couple.

Kechil Kirkham on Fine Music Radio does a regular weekly feature called Looking Up where she talks to somebody about astronomy related things, things that are happening currently, and interviewing astronomers around the country. Also, The Urban Astronomer, Alan Versfeld. Who runs a very successful podcast, very interesting stuff, and he does good interviews, again, with students, postdocs, and researchers around the country on the exciting work they’re doing.

Jacinta: [00:38:53] Yeah, definitely. Check those out. All right. I think, Dan, that that’s it for the episode and for the season.

Yeah. It’s been amazing. Thank you all very much for listening again, and we hope you’ll join us for season three of The Cosmic Savannah.

Dan: [00:39:12] As always, you can visit our website, thecosmicsavannah.com where we will have transcripts, links, and the full archive of our episodes. You can follow us on Twitter, Facebook, Instagram @cosmicsavannah That’s savannah spelled S-A-V-A-N-N-A-H

Jacinta: [00:39:29] Thank you to all of our volunteers who have helped out throughout the last year, including Thabisa Fikelepi for social  media, Mark Allnut for music production, Janus Brink for Astro-photography, and Lana Ceraj for graphic design.

Dan: [00:39:41] We gratefully acknowledge support from the South African National Research Foundation and the South African Astronomical Observatory as well as the University of Cape Town astronomy department to help keep the podcast running .

Jacinta: [00:39:52] You can subscribe on Apple podcasts, Spotify, or wherever you get your podcasts, and if you’d like to help us out, please rate and review us and recommend us to a friend

Dan: [00:40:02] and we’ll speak to you next season on The Cosmic Savannah.

Jacinta: [00:40:12] Bye!

Dan: [00:40:12] Bye

Jacinta: [00:40:19] Thank you all very much for listening again, and we hope you’ll join us for season three of The Cosmic Savannah. [Crash and laughing]

My blanket is falling down!

Dan: [00:40:31] There we go, there’s your blooper!

Jacinta: [00:40:33] It clearly knows that it’s the end of the season and it doesn’t want to hold out. It was supported by a wand, a Harry Potter wand, and it’s just fallen down.

Let’s try that again.

Episode 24: HIRAX

with Prof Kavilan Moodley

Episode 24 features Professor Kavilan Moodley who joins us to discuss another exciting project in radio astronomy in South Africa, HIRAX!

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a radio telescope array that will map nearly all of the southern sky over a frequency range of 400 to 800 MHz. The primary goal of HIRAX is to measure baryon acoustic oscillations (BAOs): these are remnant ripples in the distribution of galaxies that originate from primordial sound waves that existed in the early universe.

This can be used for charting the expansion history of the universe and for shedding light on the nature of dark energy.

All-sky map of the Cosmic Microwave Background temperature as obtained by the Planck space telescope.  Credit: ESA
A Rock Hyrax or “Dassie”

This week’s guest:

Episode Links:
HIRAX: https://hirax.ukzn.ac.za/
Planck and the CMB: https://www.esa.int/Science_Exploration/Space_Science/Planck_overview

Featured Image:
The HIRAX Prototype dishes at the Hartebeesthoek Radio Observatory, South Africa

Transcription – By Sumari Hattingh

Dan: [00:00:00] Welcome to The Cosmic Savannah with Dr. Daniel Cunnama

Jacinta: [00:00:07] and Dr. Jacinta Delhaize. Each episode, we’ll be giving you a behind the scenes look at world-class astronomy and astrophysics happening under African skies.

Dan: [00:00:16] Let us introduce you to the people involved, the technology we use, the exciting work we do, and the fascinating discoveries we make.

Jacinta: [00:00:24] Sit back and relax as we take you on a Safari through the skies.

Hello. Welcome back to episode 24

Dan: [00:00:40] yeah, welcome back.

Jacinta: [00:00:41] Yeah, Dan’s still on Skype. How’re you doing over there?

Dan: [00:00:45] Yeah. All right. Locked in the house with little kids. So if you hear the kids in the background, you know, apologies for that.

Jacinta: [00:00:52] Yeah. And I’m still in my blanket fort and I have no little kids here, so I just made one. I have no excuse. We’ve expanded it now it’s got two rooms.

Dan: [00:01:01] Do you stay in it even when you’re not recording?

Jacinta: [00:01:05] Yup. And we’ve added fairy lights now as well. All right. So what are we actually going to talk about today?

Dan: [00:01:12] We are joined by Professor Kavilan Moodley, who is from the University of Kwa-Zulu Natal, who you actually interviewed at the South African Radio Astronomy Observatory Bursary Conference, and he’s going to be talking to us about dark energy and an instrument they they’re building called “HIRAX”.

Jacinta: [00:01:30] Yeah, exactly. So, as you said, I was at the South African Radio Astronomical Observatory – SARAO – Bursary Conference in December last year, the start of December, which was held in Durban, which was really great to go visit because I haven’t had much of a chance to explore South Africa yet. Just Cape Town and a few other places.

But, so Durban was really cool. And, it’s more or less like the South African National, like annual conference, of Radio Astronomy. And so there’s radio astronomers there from all over the country. So it was a great opportunity to get some interviews with some people, not from Cape Town. And Kavi is one of those. He’s the Professor at the Department of Astronomy UKZN, and he’s one of the people leading the charge in building a new telescope called HIRAX.

Dan: [00:02:20] Yeah, we’ve spoken a lot about MeerKAT; we’ve mentioned a couple of the other instruments, which are happening….at the SKA. But in addition to MeerKAT, there are all of these other instruments which are also getting built, which have different little niches that they work in.

They work in slightly different niches. They look at different things in space and different frequencies, different wavelengths, and have different science cases. This is one of those different instruments, which is also going to be built in South Africa.

Jacinta: [00:02:52] Yeah, so it’ll be made of 1000 dishes and they’re each going to be six meters in diameter. And HIRAX stands for the Hydrogen Intensity and Real-Time Analysis eXperiment. So another contrived acronym from astronomers.

Dan: [00:03:11] It’s quite a fun one because if you don’t know what a hyrax is; a hyrax is a little, well, it’s not a rodent. But you can think of it as a rodent – it’s a little thing that looks a bit like a bunny, but doesn’t have long ears. It’s brown, and they exist here in South Africa. They run around on rocks and on mountains and things, and they’re very sweet, and we call them “dassies”. But their proper name is a “hyrax”.

Jacinta: [00:03:41] Yeah, and it’s a super cute logo with a little, a little dassie on it for those from Australia. It kind of looks like a marsupial, even though it’s not; like a little quokka that’s on, like only on all fours and doesn’t stand up. So that’s how I would describe it. Well, we’ll put a picture on our website.

Dan: [00:03:59] The other thing that is always said about a dassie or a hyrax is that its nearest relative is an elephant. It goes all the way back on its own branch, all the way back to the common ancestor of the elephant, and the hyrax, which is pretty strange.

Jacinta: [00:04:14] That is strange. The dassie can be found in the Karoo and the Karoo is where the telescope is built. So we’re looping back to astronomy there.

Dan: [00:04:23] Yeah. And then, as you said, there are thousands of these little dishes and they’re six meters across, so they’re not as big as the MeerKAT ones, which are 13 and a half meters across.

And they’re also a lot simpler. So they don’t have the same demands in terms of the surfaces or the instrumentation. And that means that it’s a very cheap experiment. And we can build houses with these things, for a fraction of the process; a MeerKAT dish.

Jacinta: [00:04:51] Yeah, exactly. But it’s not built yet. Just like the SKA is not built yet. There is a prototype that’s somewhere near Johannesburg, I think.

Dan: [00:04:58] Yes, Hartebeesthoek. The original Radio Astronomy Observatory in South Africa was in Hartebeesthoek, which is just outside Pretoria in South Africa, and there’s a large radio dish there, but now there’s the prototype for the HIRAX, and that’s just to test the instruments.

To try and get a concept together of what it’s gonna look like and then use that to try and raise funding to actually build this thing.

Jacinta: [00:05:28] Yeah. And other than the dishes themselves, one of the main differences between HIRAX and SKA is that the HIRAX dishes are all going to be kind of in a high density, small area, so they’re all going to be clumped quite close together.

Now, you might remember that radio astronomers always talk about baselines, which is the distance between two of these dishes and short baselines mean that the dishes are closer together. If you have dishes closer together, your telescope is more sensitive to larger scale, so you can see things that are larger on the sky.

Whereas if you have, your telescopes are very far apart, long baselines, they’re more sensitive to things that are small on the sky; small structures. But HIRAX wants to see the largest structures on the universe, and that’s why it’s got a high density of very short baselines. And they want to see large scales because a lot of the science case for this telescope is cosmology.

So I don’t know Dan. Well, so Kavi does explain that a bit, but it’s kind of, well, I guess it’s the universe on the larger scales. And I guess we need to start from the Cosmic Microwave Background or CMB in order to explain that. So, Dan, do you want to explain what the CMB is?

Dan: [00:06:43] So I’ll, I’ll take a stab. So cosmology is basically the study of the very largest scales, as Jacinta said, we’re not looking at individual galaxies. We are looking at the clusters of galaxies and beyond that supercluster – how the matter in the universe is distributed on the very, very large scales – are these clusters, there’s voids where there’s no galaxy.

And why is the matter distributed like that? What you want to do is, see where these large dense regions or under dense regions formed from. Where did they originate from? Why is there more matter in one place than somewhere else? And one of the ways we can work that out is by measuring this Cosmic Microwave Background.

If you look in the microwave wavelength or frequency, you can see all around the earth, and this has been mapped in quite a lot of detail, first led by Kobi satellite, but most recently by the Planck satellite. And everywhere you look there is microwave radiation, which is coming from the very, very early universe, and it has tiny fluctuations in terms of the color or temperature of that light. And those tiny fluctuations make up what’s called the Cosmic Microwave Background and those tiny fluctuations are the hint. as to why some regions will be dense and some regions will be under dense. So by mapping this very early universe and these fluctuations, we can see where matter would fall and on what scales – where it comes from and in what form; in what scale. So we can measure in quite a lot of detail what sort of scales the fluctuations are on; on the Cosmic Microwave Background.

And then if we can measure by doing a galaxy survey of our local universe or the larger universe, we can see whether those correlate, if there are a lot of galaxies on one sort of scale and the surveys, does that correlate to these initial fluctuation? And it does. A Nobel prize was awarded for this.

This was a major discovery in recent astronomy or cosmology. And this gives us a very good idea of the distribution of matter within our universe.

Jacinta: [00:09:07] Yeah, exactly. That’s a challenging thing to explain, but I think you did great. I would just add that the thing that you want to pin down is the characteristic scale of the baryonic acoustic oscillations, and that essentially is like putting a ruler onto the universe at each time. So as the universe is aging, you’re trying to put a ruler against it at all of those times and see what the typical size of certain things is. So as you mentioned, you might do a galaxy survey and you might measure the typical distance between galaxy clusters, for example. But what HIRAX is going to do – it’s not going to look at galaxies. It’s more going to look at neutral hydrogen gas, which can exist between galaxies and therefore it could be a better tracer or a different tracer of this typical scale or typical size. And the reason why you want to do – why HIRAX is doing that – is actually to study dark energy because it’s this dark energy, which is accelerating the expansion of the universe.

And that of course was another Nobel prize to several people, including professor Brian Schmidt from our community in Australia. Shout out to Brian. So you’ve got dark matter, which is essentially adding gravity and pulling everything towards each other. But you’ve got dark energy, which is kind of like anti-gravity or negative gravity and pushes everything apart.

And this effect has changed in its strength over the history of the universe. So at the beginning, sort of after the Big Bang, it was relatively weak compared to the other forces, but now it seems to be dominating a lot more. So HIRAX is trying to look at the hydrogen, measure the typical length scales, and therefore make some conclusion about dark energy and maybe that lets us figure out what it is.

Dan: [00:11:00] So we basically get a different view of a different time in the universe. So the Cosmic Microwave Background is as early as we can look at 380,000 years after the Big Bang. And we can look at these scales and fluctuation. Now we can look at the galaxies now and see those scales.  But by looking at the neutral hydrogen with HIRAX, we can look at a time in between so we can look at the early universe beyond the CMB before galaxies formed, before a lot of the galaxies formed, and as you said, then we can get an idea of what the strength of dark energy was in those times and how the matter was distributed.

Jacinta: [00:11:42] Exactly. But that’s not the only thing HIRAX can do. It’s also looking at transients. Dan, do you remember what a transient is from the last episode with Patrick?

Dan: [00:11:53] I do. Okay. A transient is basically something which is out of varying with time in terms of its brightness, or another sort of factor. Or it’s something which goes – something which happens very briefly, once-off, and doesn’t occur again.

Jacinta: [00:12:11] Yeah. And in the previous episode 23 – talking to Patrick – we were talking about one type of transient object, which can be an X-Ray binary, where you’ve got black holes or whatever, sucking stuff off their partner stars. But in this case, HIRAX is looking for fast radio bursts or FRBs for short, and we don’t really know what this is at all, but it happens on millisecond scales.

So there’s just a sudden millisecond flash of bright radio light, and HIRAX is going to try and figure out what they are. And it’s an ideal telescope to do this because it’s going to see a wide area of the sky all at the same time. So if these things are quite rare and quite brief, you need to be looking kind of everywhere at the same time in order to spot them to have a good chance of spotting them.

But because they’re quite small, you also have to have good angular resolution as you need to be able to see things on small size scales. But we’ve already mentioned that HIRAX is going to have short baselines, and so it’s actually going to be better at looking at large scales, but they’ve come up with a way to solve that, which is the VLBI – very long baseline interferometry – which we spoke a lot about in episode,… what was it, back in season one, episode five with the EHT imaging of the black hole? Do you remember Dan?

Dan: [00:13:30] I may not remember which episode it was. I do remember discussing it.

Jacinta: [00:13:34] We were talking to Roger Dean and we went into a lot of details. If you want to know more about VLBI, you can go back to that episode, but basically you put a few telescopes out really, really far away. So long, large base lines away from your central core of telescopes. And these can be called outrigger stations. And that gives you the ability to see these shorter spacings on the sky. And so you’ve got a better chance of picking up these FRBs and to localize them, which means to figure out exactly where they’re coming from because some telescopes can see them, but say, okay, it’s coming from somewhere in this area, and with HIRAX, you want to be able to pinpoint exactly where in that area it’s coming from, and that’s going to give you a better chance of figuring out what’s causing it.

Dan: [00:14:21] Yeah. So we’ve given a good overview, I think of what HIRAX is going to be doing. We should probably hear from Kavi himself, who is the PI of this project, and he will be talking to you, Jacinta, about what it’s gonna do.

Jacinta: [00:14:35] All right, let’s hear from Kavi.

…music playing…

With us now is Professor Kavi Moodley from the University of KwaZulu Natal, welcome Kavi.

Kavi: [00:14:48] Thanks Jacinta.

Jacinta: [00:14:49] Kavi, tell us who you are, where you’re from, what you do.

Kavi: [00:14:52] Yeah. So I’m a professor at the University of KwaZulu Natal, as you mentioned to the listeners. My name is Kavilan Moodley. I’m interested in cosmology and astrophysics. So, I do research in this topic here in Durban.

Jacinta: [00:15:07] Okay. So tell us about the research group at the, at UKZN.

Kavi: [00:15:10] Yeah. So we’ve been – the research group at UKZN has been growing over the last few years. We now actually have set up an astrophysics research center at the university and we have a number of undergraduate students, postgraduate students and postdocs.

And our faculty numbers are growing. So the research there has two themes. One is more theoretical, looking at studying physical processes, gravity, etc. with application to astrophysics. And the second is more observationally; observational based. And that involves taking data from a number of telescopes and also building telescopes as we all talk about. And that’s focused more on extragalactic astronomy and cosmology.

Jacinta: [00:15:57] So we’re here in Durban at the moment for the SARAO Bursary Conference 2019 – we’re in Durban. And this is where UKZN is, is that correct?

Kavi: [00:16:06] Yes, that’s right. So UKZN, has two campuses, well, actually three campuses in Durban.

There’s a medical school, the Howard college campus, which has mostly engineering and the arts and social sciences. And then there’s the Westville campus where most of the science and management science are, and there’s another campus in Pietermaritzburg. And the education campus in Pinetown.

Jacinta: [00:16:28] So I came up early for the conference for the weekend just to check out Durban a little bit.

I just ended up kind of staying by the beach cause there’s a nice beach. The water is a lot warmer than in Cape Town and it’s kind of very tropical, lots of green all the way down to the beach. Tell us a bit more about Durban for our international listeners.

Kavi: [00:16:45] Yeah. Durban is fantastic. The weather is great all year round. There have been many reviews that have awarded it in one of the best destinations, including CNN and, you know, other websites though. Yeah, the water is warm so you can swim all year round. It’s a great location for getting access to the wildlife parks when you’re two hours away or the mountains; the Drakensberg is also two hours away. So, and Durban itself is interesting. It’s quite multicultural. People from many parts of the world are here. And you know, green rolling hills and, the food is interesting; very diverse.

Jacinta: [00:17:22] Yeah. I was just about to say the food. There’s the famous Durban curry and bunny chow.

Kavi: [00:17:27] Yeah, and that’s, I guess, part of my legacy being of Indian origin. So it’s quite exciting, but there’s quite an interesting multicultural mix in Durban.

Jacinta: [00:17:38] And, what exactly is bunny chow? I’ve been meaning to ask someone local from Durban.

Kavi: [00:17:43] It’s a, basically a hollowed out, a fraction or quarter or half of a loaf of bread, where the bread is not sliced and then it’s followed with the spicy curry.

Jacinta: [00:17:54] All right. Back to science. What research do you do in particular?

Kavi: [00:17:58] So my primary research interest is in cosmology. I’ve worked on the Cosmic Microwave Background or still work on in that area. And more recently I’ve moved into working on cosmology from using radio observations, generally trying to understand what the universe is made of – these mysterious components of dark matter and dark energy and just how galaxies form and evolve.

Jacinta: [00:18:24] What is the difference between astronomy and cosmology?

Kavi: [00:18:27] I guess maybe just terminology. Astronomy is interested in probably a wider variety of phenomena in the universe, and one would say it incorporates cosmology because cosmology is the study of the universe on the largest scales, including the large scale structure that we see; the Cosmic Microwave Background and a variety of other probes. Astronomy extends to studying stars, planets, galaxies. So one could say that astronomy covers scales that are much smaller than we study in cosmology.

Jacinta: [00:19:03] Right. And so as part of studying this cosmology, is it correct to say that you are helping in the development of something called the HIRAX telescope?

Kavi: [00:19:12] Yes. As I alluded to earlier, HIRAX is a project we are driving here out of UKZN and has a number of partners in South Africa and international partners. The goal is to build a radio interferometer array so that’s a collection of roughly a thousand dishes that are six meters in diameter. And unlike MeerKAT or other radio interferometers, the HIRAX will be a very compact array rather than the dishes being spread out.

And the idea there is that you have a lot of sensitivity to large scales, you know, which you need to map out the large scale structure in cosmology.

Jacinta: [00:19:51] First of all, tell us about the name HIRAX.

Kavi: [00:19:54] So the name HIRAX – it’s an acronym for the Hydrogen Intensity mapping and Real-time Analysis eXperiment.

It was cleverly devised because it’s the Latin name is Hyrax, spelled with a Y, not an I, refers to the rock dassie, which is a resident of the crew, like the MeerKAT is. And so HIRAX will be located in the Karoo site.

Jacinta: [00:20:20] So Hyrax is a little animal.

Kavi: [00:20:22] Yes. Actually a related, its closest relative is the elephant.

Jacinta: [00:20:26] Oh really? But it’s a tiny little animal, isn’t it?

Kavi: [00:20:29] One would think that it has relatives, which are more furry.

Jacinta: [00:20:32] So you’ve said that this is a thousand dishes in the Karoo near the SKA site?

Kavi: [00:20:37] Yes. It’s about 15 to 20 kilometers and currently we have actually funding up to 256 dishes, but we’re planning to expand to a thousand dishes.

Jacinta: [00:20:48] How is it different to the SKA?

Kavi: [00:20:51] The SKA has different scientific applications. Since we’re interested in cosmology in particular, we are trying to map out the hydrogen in the universe, but not on scales of the galaxy, but on much larger scales. We’re looking for a signal that’s a on scale a hundred times larger than the typical separation between galaxies. So to get sensitivity to very large scales, we need to have a very compact array. Conversely, if you want to discover things on very small scales, you have very long baselines. So you put your dishes far apart. And that’s what the SKA and MeerKAT are aiming to do.

Jacinta: [00:21:34] Right, so MeerKAT and the SKA are going to excel in sort of high resolution stuff, where you’re looking at smaller scales, smaller objects, whereas HIRAX is just to see huge large scale stuff. Is that correct?

Kavi: [00:21:47] Yes. That’s right, the volume that HIRAX will map out in the universe will be significantly more than many of the surveys that are will be undertaken by MeerKAT or the SKA.

Jacinta: [00:21:58] All right, and what are the main science goals of HIRAX?

Kavi: [00:22:01] There are two leading science goals. The primary one is, of course, dark energy, and the idea is to use the distribution of hydrogen in the universe on the very largest scales to map out a feature called the baryon acoustic peak. And that’s a characteristic scale.

As I mentioned, it’s quite large compared to the size of galaxies; 150 megaparsec so over around about 450 million light years. To do that, we need to map out a large volume in the universe. Once we measure the baryon acoustic feature, that gives us a unique lens scale, which we can then track over time because we measure the hydrogen at different frequencies and with that lens scale, we can then set a constraint on dark energy.

Jacinta: [00:22:51] So this is essentially a big telescope to study dark energy.

Kavi: [00:22:55] Yes, that’s right. Yeah. That’s its primary goal because we have a compact array, another important application of the telescope will be to discover transient phenomena and in particular fast radio bursts, which are a very hot topic at the moment, and pulsars,

Jacinta: [00:23:11] Okay, so what’s a transient and what’s a fast radio burst.

Kavi: [00:23:14] So a transient is an object in the universe that appears for a very short time. Fast radio bursts, for example, are very bright flashes in the radio sky – as bright as some of the other objects in the radio sky, and they only last for a very short duration, maybe a millisecond. Until recently, we’ve only had a handful of detections of these fast radio bursts, mainly because you need to cover a large area of sky and you need a broadband to detect these objects. Recently, a telescope like CHIME have changed that and are we now detecting hundreds of fast radio bursts. So HIRAX will be well positioned to detect lots of fast radio bursts in the Southern sky because it has a large collecting area and it has a large area.it surveys on the sky.

Jacinta: [00:24:05] And there any theories as to what could possibly be causing fast radio bursts?

Kavi: [00:24:11] Yes, there’s many theories out there. In fact, at one point there were more theories than they were actual detections of fast radio bursts. It’s pointing to some energetic event in the universe.

Probably the collision of, or the merger of, two massive stars is one theory. There’s a vast number of models out there, and collecting more data will help us to narrow down the range of models that we see.

Jacinta: [00:24:38] So HIRAX will hopefully help us figure out what is causing these things, right?

Kavi: [00:24:42] Yeah. And I think a key advance that we will make with HIRAX, which are the projects are also attempting, is, to try to localize these objects. Currently, it’s difficult to simultaneously survey a large area on the sky, and then have good angular resolution to pinpoint where they’re coming from. So typically, the localization of these FRBs, in the region where they’re detected, could be hundreds of galaxies.

So what HIRAX is hoping or is planning to do, is to have very long baselines, which would give us higher resolution. So we plan to build a small outrigger stations of about eight dishes. And place these working together with partners in other African countries at remote sites in these partner countries, and then do long baseline interferometry with these signals that will allow us to detect these FRBs.  And simultaneously localize them to within the galaxy, not just in a particular galaxy, but within a spiral arm in the galaxy.

Jacinta: [00:25:50] Okay, so you have HIRAX, which is a lot of dishes close together so that you can see large scale things, but also you want some telescopes associated with HIRAX, much, much further away from this compact central region so that you can do very long baseline interferometry, as you’ve said. And so therefore, if we can also see smaller details, therefore you can localize – so find out where the burst is coming from. So, which of these partner countries throughout Africa will potentially have some of these outrigger stations of telescopes?

Kavi: [00:26:21] We’re in discussion with a number of interested partners. Currently the most advanced partners are Rwanda and Botswana. We’re also in discussion where people from Namibia, Mauritius and potentially Mozambique and Kenya – but those are less advanced. So, in addition to the African partner companies, we have a HIRAX prototype at the Hartbeestboek Radio Observatory just outside of Johannesburg – that’ll also serve as another outrigger station. So we plan to start off with two or three outrigger stations before we expand to other partner countries. These stations are relatively easy to deploy because they just comprise eight dishes.

Jacinta: [00:27:06] So this has the potential to be quite a pan-African telescope.

Kavi: [00:27:10] Yes. And we’re hoping that we can contribute just a little in growing the interest in astronomy around the continent and in particular radio astronomy. These arrays are fairly easy to get up and running, and they would, they make excellent instruments for students and researchers to get their hands dirty.

Jacinta: [00:27:31] Yeah, exactly. There’s nothing like actually being at the telescope for the dish to boost your interest and your learning. Now, I wanted to get back to dark energy because we very briefly skipped over that, but it’s so interesting. Okay. Let’s just go through what is dark energy and why don’t we know what it is yet?

Kavi: [00:27:47] So dark energy is this mysterious form of energy, a component in the universe, which causes the universe to actually accelerate in its expansion. So if we had the regular matter, like the stuff that we’re made of and that we see around us, we would expect the universe to stop or slow down in its expansion, because the matter is putting it back.

However, a dark energy has a negative pressure and that’s almost like a repulsive gravity, and therefore causes the universe not to slow down in its expansion, but actually just speed up. So you may say negative pressure. That’s weird. And it is weird. It’s a strange stuff that we’re talking about.

The closest thing, and probably the best theory for dark energy at the moment is something called the cosmological constant, which Einstein proposed. Giving it a name doesn’t mean we know what it is. People think that it’s some form of the energy of the vacuum. So in the absence of all matter, this would be the only energy present.

But the theoretical predictions for this vacuum energy differ vastly by many orders of magnitude from what we observe for the value of the energy today.

Jacinta: [00:29:03] How is HIRAX going to help us figure out what it is?

Kavi: [00:29:06] So HIRAX will, as I mentioned, measure the large scale distribution of hydrogen in the universe that hydrogen chases the large scale structure.

And that structure has imprinted in it, something called the baryon acoustic peak, which is a unique lens scale that we can predict very accurately. So we will measure this lens scale with a percent level measurements and we will not just do that at one instant in time, but we will do that over a wide range of time.

So HIRAX will observe from about 11 billion years ago. To about 7 billion years ago. And that’s an important epoch because that is when dark energy was becoming important in the universe and was beginning – or starting after that period is, when it became dominant in the universe. So we will be able to measure how the universe – this lens scale – changes over time, over a wide range of time. And that will tell us what the behavior or properties are of dark energy.

Jacinta: [00:30:09] Okay, so it’s at least going to help us to understand more about the properties of dark energy and maybe that will lead us towards what it actually is.

Kavi: [00:30:19] Yes in particular, I mentioned the cosmological constant, that has a fixed equation of state, which is the ratio of the pressure to the density and its value is minus one, so it has negative pressure.

What we are hoping to do is to determine if they are deviations from that equation of state. So if the ratio is not minus one, that would point to very interesting new physics.

Jacinta: [00:30:44] Oh, lots of mysteries that HIRAX will help us solve. And when can we expect this telescope to be ready?

Kavi: [00:30:49] So at the moment, we are putting out a tender or bid for dishes for the telescope.

So that’ll be early next year. And we hope to by the end of having testing these dishes to install them at the Karoo site in South Africa.

Jacinta: [00:31:07] Great. And do you have any final messages for listeners?

Kavi: [00:31:11] Yeah. I’d like to direct the message to the young people out there who are fascinated by science and astronomy.

Certainly pursue your passion and it’s a hard journey, but don’t give up and you’ll be rewarded for it.

Jacinta: [00:31:25] Wonderful. And if people want to find out more about you and your research group and HIRAX, where can they go?

Kavi: [00:31:31] And you can look up the astrophysics and cosmology research unit.

ACRU , which is at UKZN, and we have a website. HIRAX also has a website which is hosted at UKZN. so it’s H-I -R-A-X-dot-U-K-Z-N-dot-ac-dot-za.

Jacinta: [00:31:47] And can we find you anywhere on social media?

Kavi: [00:31:49] We have an active social media presence through our research unit. So certainly if you look for ACRU on Twitter, Facebook, you could catch up with me indirectly through those social media platforms.

Jacinta: [00:32:04] Thank you so much for speaking with us today, Kavi, it’s great, to catch up with you as always.

Kavi: [00:32:08] Thanks very much Jacinta, and I hope you have a good day.

… music playing…

Jacinta: [00:32:20] So a lot of great science there. I do also have to admit, Dan, that I didn’t taste bunny chow in Durban because I can’t really handle a lot of spice.

Dan: [00:32:30] Well, you missed out.  I don’t know if the listeners know: I grew up in KZN. So I grew up on bunny chow – it’s delicious. I mean, it’s very high on the carbs because you’re having a lamb and potato stew inside half a loaf of bread. Yeah.

Jacinta: [00:32:51] You wouldn’t want to go back to work after that. You’d be very, very drowsy. Food coma.

Dan: [00:32:58] Yeah. You know, delicious. I could do one right now. I’m sure

Jacinta: [00:33:02] I tried one in Cape Town once, but I think it was like a really watered down Cape Town version ‘cause it wasn’t very spicy.

I want to know what dark energy is. Getting back to science again.

Dan: [00:33:15] I don’t we all, and I think that that’s one of the nice things. This is another great project, which is getting both in South Africa, and maybe we’ll answer some of those questions or at least get closer to answering those sorts of questions.

It’s great. We hear a lot about MeeerKAT. We hear about SALT and some of the other big projects that are going on, but there’s a lot of these other projects happening too. We’re exploring a lot of different realms of science all at the same time and it’s exciting.

Jacinta: [00:33:45] Yeah, definitely lots of different things.

It was a bit refreshing to talk about radio astronomy, that’s not MeerKAT, even though I love it. There are other instruments out there. Well, all of that talk about bunny chow. I kind of want to go and get some lunch now.

Dan: [00:34:00] Yeah, me too. All right. Thanks for joining us again, and we hope you’ll join us on the next episode of The Cosmic Savannah

Jacinta: [00:34:07] In the meantime, you can visit our website, thecosmicsavannah.com where we’ll have the transcript of this episode and related links. You can also follow us on Twitter, Facebook, and Instagram @cosmicsavannah, that Savannah spelt, S-A-V-A-N-N-A-H. Thanks to Sumari Hattingh, Brandon Engelbrecht, Lynette Delhaize, and Thabisa Fikelepi for social media and transcription assistance.

Also to Mark Allnut from music production, Janus Brink for the Astrophotography and Lana Ceraj for graphic design. We gratefully acknowledge support from the South African National Research Foundation, the South African Astronomical Observatory, and the University of Cape Town Astronomy Department to help keep the podcast running.

You can subscribe on Apple podcasts, Spotify, or wherever you get your podcasts. And if you’d like to help us out, please rate and review us and recommend us to a friend and we’ll speak to you next time on the Cosmic Savannah.

…music playing…

Dan: [00:35:13] All right. Thanks for joining us again, and we hope you’ll join us. Argh!

This is why we have a script

Jacinta: [00:35:25] so that you can not read it!

Episode 23: ThunderKAT

with Prof Patrick Woudt

In Episode 23 of The Cosmic Savannah podcast, we are joined by the Head of Astronomy at the University of Cape Town, Professor Patrick Woudt.

Prof Woudt joins us to talk about an exciting project he is involved in using the MeerKAT radio telescope, namely ThunderKAT (The HUNt for Dynamic and Explosive Radio transients with meerKAT). ThunderKAT is looking for explosive things that flash in the radio sky!

The project has recently observed a black hole ejecting material at close to the speed of light out to some of the largest angular distances (separations) ever seen. These observations have allowed a deeper understanding of how black holes feed into their environment

Featured Guest

Featured Image:
South Africa has already demonstrated its excellent science and engineering skills by designing and building the MeerKAT radio telescope – as a pathfinder to the SKA. The 64-antenna array is located at the SKA site at Losberg in the Karoo, about 90 kilometres from Carnarvon. Credit: SARAO (South African Radio Astronomy Observatory).

Related Links:
News article: https://www.news.uct.ac.za/article/-2020-03-02-shedding-new-light-on-black-hole-ejections
ThunderKAT: http://www.thunderkat.uct.ac.za/
MeerKAT: http://www.ska.ac.za/
MeerLICHT: http://meerlicht.uct.ac.za
SKA: http://www.skatelescope.org/


(By Brandon Engelbrecht)

Jacinta: [00:00:00] Welcome to The Cosmic Savannah with Dr. Jacinta Delhaize 

Dan: [00:00:08] and Dr. Daniel Cunnama. Each episode, we’ll be giving you a behind the scenes look at the world-class astronomy and astrophysics happening under African skies. 

Jacinta: [00:00:17] Let us introduce you to the people involved, the technology we use, the exciting work we do and the fascinating discoveries we make.

Dan: [00:00:25] Sit back and relax as we take you on a Safari through the skies.

Jacinta: [00:00:32] Hello everyone. Welcome to episode 23. Dan is joining us from home via Skype. 

Dan: [00:00:38] Yeah. We’re all under lockdown. For the next little while, we’ll be having to do our recording via skype.

Jacinta: [00:00:44] Yeah, so of course, this is because of the coronavirus outbreak. South Africa has gone into lockdown now. Uh, like most of the world and we were considering whether or not to put out this episode weren’t we Dan?

Dan: [00:00:58] Yeah, but I think it’s, I think it’s good. I think that people are going to need some stuff to listen to and hopefully we can provide that. 

Jacinta: [00:01:05] Yeah, I hope so too. Um, we all want a distraction. We all want to, you know, talk about something different and learn something new. So why not go ahead with that.

We’ll just have to put up with some low-quality sound from Dan’s end for a little while, but I think it’s okay and I’ve taken the recording equipment back to my house and I’m literally sitting in a blanket fort, which I made for myself for soundproofing. 

Dan: Very professional.

Jacinta: Yes, definitely. I’m going to put a picture of it on the social media so you can have a look. I’m very proud of it. Right. Okay. So what are we talking about today, Dan? 

Dan: [00:01:40] So today we’re joined by Professor Patrick Woudt he is the Head of Astronomy at the University of Cape Town here in Cape Town and he’s also the principal investigator for the ThunderKAT project, which is a large science project on the MeerKAT telescope. 

Jacinta: [00:01:59] As we’ll talk about further when we chat to Patrick, the LSPs, as we call them, Large Science Projects are what MeerKAT is mostly going to be focused on during its run time and ThunderKAT is one of those.

It stands for The Hunt for Dynamic and Explosive Radio Transients with MeerKAT, if you can figure that one out,  how they got to that acronym.

Dan: Just another contrived acronym

Jacinta: Oh, astronomers love it. Okay and so this is a survey in the radio with MeerKAT to look for transients. 

Dan: [00:02:30] Yeah. So what is a transient?

Jacinta: [00:02:32] A transient is something that goes bang, basically an explosion, uh, in space. It’s something that wasn’t there before and then happens now. It is a transient event. So it happens sometimes and not at other times and one of these objects that ThunderKAT is going to be looking at is X-ray Binaries.

Dan:  And what is an X-ray Binary?

Jacinta: Well, we did talk a little bit about it in episode 21 I think with Tanya Joseph, she talked a lot about these X-ray binaries. A binary is two stars going around each other and often one of these stars is a compact object. A compact object is something like a white dwarf or a neutron star or a black hole, something that’s, the fossil of the end of a star’s life and often it means that this compact object is going to be sucking material off its companion star, which is still a big normal star with gas on it and as this happens, it can release X-rays and then it’s called an X-ray binary. 

Dan: [00:03:38] Yeah. So you’re basically looking at two stars, what was two stars orbiting around each other. One of them has now gone compact and the other one is just a regular star, right?

Jacinta: [00:03:48] Yeah, exactly and part of what ThunderKAT going to do is that they, there is several known X-ray binaries and there are X-ray telescopes looking at them and then MeerKAT is going to regularly look at the same binaries in the radio and check whether they’ve changed if they’re releasing more or less radio waves and then figure out what that means.

Dan: [00:04:09] And this is exactly what we’re gonna be talking about today right because they have already spotted one. 

Jacinta: [00:04:13] They have actually found a new one while they were looking at one of these transients that they already knew existed. They spotted a new one and they’ve got a paper out on that and they also found one of these transients that they were monitoring doing something new and crazy.

And so they’ve published that in Nature Astronomy, which is quite a prestigious journal. They found that this object was emitting X-rays, so there was accretion happening, which means that the compact object is sucking in gas from its companion star, but then they found something special happening in the radio data with MeerKAT in that it was releasing jets.

So like huge ejections of material of matter, electrons and stuff near the compact object and it was being thrown out into space in one of the most energetic processes ever seen for this kind of event and being thrown out to one of the largest distances. 

Dan: [00:05:09] Yes. I mean, it’s a very exciting discovery and great to see that these sorts of discoveries are already coming out of MeerKAT and some of the MeerKAT projects. 

I think that we should probably speak to Patrick, who will tell us about all about it and also about the couple of other things we spoke to them about, such as the UCT Astronomy Department’s 50 year anniversary and the MeerLICHT telescope that we have mentioned once before.

Uh, which is another one of these multi-wavelength, a collaboration between MeerKAT and in this case, an optical telescope.

Jacinta: [00:05:41] Yeah. Great. Let’s hear from Patrick

With us, in the studio today is Professor Patrick Woudt, who is the Head of Department for Astronomy at the University of Cape Town. Welcome, Patrick. 

Patrick: Hi Jacinta. 

Dan: [00:05:57] Welcome to The Cosmic Savannah. 

Patrick: [00:05:58] Hi Daniel. 

Jacinta: [00:06:00] So Patrick, you are actually my big boss, I guess. Tell us about yourself. 

Patrick: [00:06:06] I’ve been in South Africa for a long time. I did my PhD at the University of Cape Town, finished in ‘97 on large scale structures of galaxies under the supervision of Tony Fairall.

And I used many of the telescopes in Sutherland during that time. I went to ESO as a postdoc afterwards for two years and I came back to South Africa in 2000 and I’ve been here ever since, initially as a postdoctoral fellow and later as a senior lecturer, associate professor and now professor in the department.

Jacinta: [00:06:35] So you are from the Netherlands originally. But you’ve spent most of your career here in South Africa.

Patrick: [00:06:39] Indeed, yes. So I grew up in the Netherlands, did my first degree in The University of Groningen. Um, but then as I said,  in 95, I came to South Africa. 

Dan: [00:06:47] and you’re now the Head of the Astronomy Department, at UCT, right?

Patrick: [00:06:50] I am indeed. I’ve been for the last five years already. 

Jacinta: [00:06:54] And you also have another role. You are one of the PIs, the principal investigator, of the ThunderKAT project, which is an LSP and that’s a “large science project” for MeerKAT. So we know from our previous episodes that MeerKAT is a big radio telescope in the Karoo in South Africa and most of the time we’ll be doing observations for these LSPs.

So these were proposed many years ago and went through a rigorous selection committee and in several of the large projects were chosen probably taking what, hundreds or thousands of hours, each and a ThunderKAT was one of those. So tell us about ThunderKAT. You’re actually the first PI of an LSP that we’ve interviewed 

Patrick: [00:07:38] I’m honoured.

Jacinta: [00:07:40] So tell us about ThunderKAT 

Patrick: [00:07:41] ThunderKAT is a large program on MeerKAT, which aims to study the accretion, the mass transfer of gas from one star to another and these are very compact binaries. So they complete one binary orbit, for instance, in about an hour, an hour and a half. If you compared it to the Earth going around the Sun, in one year or here you’ve got two stars, one very compact, the size of the Earth, the other one maybe the size of the Sun, completing one binary orbit in an hour and a half.

So that means they are very close together and when they’re that close together, they transfer mass and sometimes at mass when it’s transferred onto the compact central star, the most massive star, very exciting things happen. You get sort of explosions that throw material back into the interstellar medium and that sort of outflow, that mass ejection you can study in the radio.

Dan: [00:08:32] In this situation with compact binaries, the compact object is the more massive of the two right? And the Sun-like object or star-like object, that’s the one that’s losing its mass and slowly getting devoured by the compact object. 

Jacinta: [00:08:49] Surely the compact object can’t be a normal star. If it’s the size of the Earth?

Patrick: [00:08:53] That’s right. So, so in my case, the objects that I study are the compact star is called what’s called a white dwarf, which is the end product of what our Sun eventually will become. But there are other compact stars like neutron stars and black holes, stellar-mass black holes that are even denser, more denser than the, than a white dwarf.

And so a neutron star has, has the mass of 1.4 times the mass of the Sun, but it’s the size of Cape Town, for instance, sort of 10 kilometres in size. 

Dan: [00:09:20] So we’ve spoken previously about X-ray binaries. So X-ray binaries are basically a subclass of these compact binaries. You can have a binary system with a white dwarf as you are studying and then as you just mentioned, a compact binary with a black hole or a neutron star which are even more compact and these white dwarf boundaries that you are studying, they’re obviously not visible in X-ray?

Patrick: [00:09:46] They do have X-ray emission, but, um, so the different wavelengths trace the different components of such a binary. So in the white dwarf accreting binaries, um, the ultraviolet is the proxy for mass transfer.

If the ultraviolet emission is very strong, the mass transfer is very high. The radio is the proxy for outflow from the system through various emission mechanisms. In neutron stars, the proxy for accretion is not the ultraviolet, but even higher energy emission mechanisms, which is the X-ray. So when you study X-ray binaries, so you want to study them in X-ray to study the accretion onto the neutron star and in radio to probe the outflow that’s been induced by that accretion. Some of that material, excess material then gets thrown off the system.

Jacinta: [00:10:34] Okay, so there’s a normal star and then there’s a compact object, like a black hole or a neutron star or a white dwarf and you’re saying that some of the, the outer layers of this big star is being drawn onto this small compact object.

Patrick: That’s right.

Jacinta: If we see X-rays coming from this system, if we can detect the object in X rays, then that means that it is undergoing this process of accretion. So where the outer layers are being pulled onto the compact object and if we see it in radio waves, then that’s telling us that there is this sort of outflow, these big ejections of, of matter shooting into space.

Is that right? 

Patrick: [00:11:13] That’s, that’s right. 

Dan: [00:11:13] So what is the mechanism for these outflows? You’re talking about mass falling onto a compact star. Why do we expect an outflow? 

Patrick: [00:11:21] Yeah, so there are different kinds of mechanisms in these binary systems, in the systems that I am most familiar with, the white dwarf accreting systems, you can have a cataclysmic outflow, which is a thermonuclear runaway on the surface of the white dwarf, which ejects the accreted material in an explosion and it blows it off at very high velocities, up to maybe a 10,000 kilometres per second, which is incredible; an incredible injection of energy. But they’re also more sedate ways of outflow and that, we haven’t talked about this yet, but the mass transfer from the companion star to a white dwarf normally goes through an accretion disk and sometimes that accretion disk gets into a higher state or hotter state, which allows the mass to flow more efficiently onto the white dwarf.

And you can have all sorts of wind mechanisms that blow material off. So you can have collimated winds creating an outflow. 

Jacinta: [00:12:13] Okay. So you can have a thermonuclear detonation of the white dwarf, or you can have the star’s layers being pulled towards the compact object and in a disk sort of like a dinner plate shape, right?

Going around this compact object and then sort of trickling onto the compact object, right? 

Patrick: [00:12:32] That’s correct

Dan: [00:12:33] So this isn’t happening all of the time right? These things are gonna have these little explosions, these outflows and then they’re going to disappear. 

Patrick: [00:12:39] Yeah. So, so these binaries, they exist in a galaxy. There’s not many.

If you have a normal star, the fraction of having these sort of binaries requires a specific evolutionary pathway that leads to this close compactness at the most extreme and you can have two white dwarfs orbiting each other every five minutes, but those are extremely rare. The process of mass transfer is a very sedate one, it moves material into a disc, sometimes the disc goes into an outburst and the system brightens up. You can see that. For these cataclysmic variables, as we call them, that happens maybe once every month, in the process, and lasts a couple of days and then it goes back into a quiescent state. The nova outburst that, happens on the white dwarf that can happen on time scales of once every thousand years or, or once every few hundred years.

There are a few known in the galaxy that recur on a timescale of 20 years or 30 years, but typically that’s a much longer process. 

Dan: [00:13:38] You’ve just published a paper on one such detection using MeerKAT. How exactly when these things are rare, how is, how is MeerKAT picking these up? Are you looking all the time for them or what is the strategy for finding these?

Patrick: [00:13:51] That’s an interesting question. So with MeerKAT, we’ve been using the telescope now since July 2018 a little over a year and a half and what we do in this particular program to study the X-ray binaries, so the accreting neutronl stars and black holes is to monitor a number of systems that are active and we know that they are active from the X-ray emission, what we discussed earlier.

So when you see X-ray emission, you know that there’s active accretion going on. So we follow active systems through X-ray monitoring. There are a number of X-ray satellites that pick these objects up and once we see them, we include them into our weekly monitoring list on MeerKAT once a week. We have a monitoring slot where we typically sample maybe four or five of these systems, for 10 or 15 minutes. It can be quite a short exposure because MeerKAT is so sensitive. 

Jacinta: [00:14:43] Oh, wow. I didn’t realize it was so short. So this is the ThunderKAT project?

Patrick: [00:14:47] That’s right 

Jacinta: [00:14:48] From past research and observations. You already know where these binary systems are, is that right?

Patrick: [00:14:53] Mostly, but some are new.

Jacinta: [00:14:54] Some are new, okay and then you can see them because they’re in the X-ray, which is picked up by a different telescope, is it SWIFT?

Patrick: [00:15:01] SWIFT is one of the telescopes that’s very good for monitoring. This particular one that we just published in Nature Astronomy is called MAXI J 1820+07 that just tells you where it is in the sky.

But the MAXI telescope is an X-Ray telescope that’s housed on the international space station. 

Jacinta: [00:15:17] Cool! So this is obviously up in space. We need it to be above our atmosphere, which absorbs all of the X rays. All right, so these are, the telescopes are spotting these flashes of X-ray. So we know that something special is going on in these binary systems, probably some accretion and then, would this weekly monitoring program you have with MeerKAT, you go on and look at these systems with our radio telescope. 

Patrick: [00:15:40] That’s right. 

Jacinta: [00:15:40] Yeah and then what do you see? 

Patrick: [00:15:42] We make images of these things. So we look at this variability or this time-domain astronomy, if you wish, with MeerKAT making images of the data and so we can spatially resolve phenomena that are related to such and such an event. So some of these systems, X-ray binaries are known when they are in this heightened state of mass transfer to eject a transient jet that comes from the system the jet moves at very high velocities, almost the speed of light and sometimes they appear to go faster than the speed up light, but it’s just a projection effect. What we do in this monitoring campaign is to study the behaviour of the X-ray binary during this bright state to understand how accretion is linked to outflow, how the accretion probed by the X-rays is linked to outflows as probed by the radio emission and in this particular case we saw the transient jet resolved in the image and move away at very fast, proper motions on the sky. So we could see the two jets on either side of the binary move very fast. 

Dan: [00:16:45] A couple of things that a transient, a transient jet is something which just happens once. It happens for a short period of time?

Patrick: [00:16:53] So in these systems, when the X-ray binaries and acquires a mode of accreting it is thought to have a permanent jet that ejects particles and when the accretion switches on that permanent jet gets disrupted. So the accretion disk then dominates and a transient jet is sort of ejected at that point. So transient with transients we mean something that varies with time. 

Jacinta: [00:17:15] Okay, so something that’s not always on, right? ThunderKAT has already put out its first publication, is that right? It came out in Nature Astronomy Journal on the 2nd of March this year, 2020 and Nature Astronomy is quite a prestigious journal. Meaning it’s a very important discovery. So tell us from the start, what this discovery was. 

Patrick: [00:17:36] This particular observation made it into Nature Astronomy because it told us something new and something special about the bay X-ray binaries for a number of reasons. So we were looking at a X-ray binary that suddenly went into a high state of mass transfer.

We took images with MeerKAT over a long time about three months after the outburst, till half a year after the outburst and from that time series of images that we took, we could see two blobs, blobs, for lack of a better word, blobs on the sky, moving at very fast, apparent motion on this sky that was associated with this ejection of material.

Jacinta: [00:18:15] And do you know what the compact object was?

Patrick: [00:18:17] In this case, the compact object is a black hole, stellar-mass black hole. 

Jacinta: [00:18:20] So it’s a black hole going around a normal star. 

Dan: [00:18:23] The other way around. 

Jacinta: [00:18:25] The black hole one has more mass than the other, right 

Patrick: [00:18:28] Going around the common centre of mass. 

Jacinta: [00:18:31] That’s our undergrad physics coming back to us. Okay so you saw these two blobs on the sky with radio and you mentioned that one of them seems to be superluminal, which is this beautiful word that means travelling faster than the speed of light. So what’s going on there? 

Patrick: [00:18:48] The jet itself is moving close to the speed of light. And the approaching jet, because it’s closely aligned to our line of sight, it appears to be moving faster than the speed of light, but this is an apparent effect. It’s just a geometric effect that you can easily calculate. You could work out what the actual velocity is based on that. The real key aspect of this particular observation is that we observed it with MeerKAT which has 64 antennae based over an eight-kilometre baseline, giving you a specific resolution.

At the same time, we’ve also observed with the eMerlin radio telescope in the UK, which is an array of telescopes over the full length of the UK, giving us a much higher resolution image and so we were able to resolve the relativistic ejector on two different scales and by doing that, we can calculate the energy of the injection of energy into these jets.

And that wasn’t done before and we realized that the energy that was launched into these jets was much larger than we previously thought. So that was the new insight into the behaviour of X-Ray binaries and black hole ejections.

Dan: Relativistic ejector?

Patrick: Moving at the speed of light or close to the speed of light.

Dan: [00:20:04] You just throw that one in there hey? So, so basically this is the, so you’ve managed to measure the energy which this gas was thrown out of the system. 

Patrick: [00:20:14] That’s right. By observing it with two different telescopes at the same time, but different resolutions and that allowed us that, that extra insight. 

Dan: Very cool.

Patrick: So you mentioned earlier this was the first paper, but in fact, we have eight papers out already on ThunderKAT. 

Jacinta: [00:20:28] Oh really? 

Patrick: [00:20:31] Yeah.

Jacinta: Oh my goodness. I didn’t realize there are so many

Patrick: Exactly so there is a whole range of papers. We’ve discovered our first radio transient and it’s turned out to be a very unusual binary star and that paper was published also earlier this year by Laura Dressen, who’s a PhD student in Manchester.

Jacinta: [00:20:43] What was it? This weird system that you found.

Patrick: [00:20:46] In this case, it was a stellar binary of a star that is very active chromospherically, very active. So the Sun sometimes has chromospheric activity. This particular star is very active. It’s called an RS CVN binary named after its prototype. It has a 22-day periodicity and SALT was able to take spectra to confirm its nature and so with the radio, we could see it move up and down in brightness. Sometimes it wasn’t there at all. Sometimes it was, they’re very bright and so on this weekly monitoring schedule that we do, we are, we are hoping to find many, many more of these radio transients.

And this was the first one of its kind. 

Dan: [00:21:27] You’ve detected all these things with ThunderKAT. For the one we were just talking about, the compact object. You followed up with another radio telescope and for this one, you were following up with SALT, is there a formal program for following up these things in different wavelengths for when you find a transient object, do you have the capacity to follow up with other telescopes immediately?

Patrick: [00:21:50] This is a very good question. The nature of this, this kind of astronomy is very much multi-wavelength astronomy. We mentioned earlier that the X-rays trace parts of the physics of these binaries, the radio traces another part of the physics. 

In the optical with spectroscopy, we can characterize the binary using optical spectroscopy to see what the nature of the stellar component is or stellar companion is and so ideally you want to have a network of telescopes around the world that can follow these things simultaneously or quasi-simultaneously. Now, when we designed the survey to find all these new objects in the radio data trying to make MeerKAT and later the SKA has a transient discovery machine.

This particular question came up, how do we characterize these systems at other wavelengths? And so that’s when Paul Groot, who’s a colleague of mine, and Rob Fender and myself, sat together and said, well, let’s build our own telescope, the MeerLICHT telescope that will follow in real-time wherever MeerKAT is looking at the same part of the sky.

So we have an optical telescope that will always co-observe with MeerKAT. So if we find something, we will know in optical, what that part of the sky is doing and we can then relay that automatically almost directly to telescopes like SALT. There is a program on SALT that allows for immediate or very fast follow up of any, any unusual kind of behaviour.

Dan: [00:23:15] So that is basically that MeerLICHT, this optical telescope, tracks wherever MeerKAT is looking and the moment that something is identified as with MeerKAT, you see if it’s also visible in the optical. 

Patrick: [00:23:32] That’s right. 

Dan:  and then if necessary, you can follow up with a larger telescope such as SALT

Patrick: That’s right. 

Dan: [00:23:33] So then on what sort of timescale are you analyzing this data? Is the ThunderKAT data analyzed instantly? 

Patrick: [00:23:39] Almost instantly. The aim is to do it in real-time. What we’re doing at the moment is that once the data gets taken from the Karoo, from where the telescope is, it gets moved to the archive, the South African Radio Astronomy Observatory archive and we pull it into our cloud-based compute resource at the university.

There’s the Inter-University Institute for Data-Intensive Astronomy (IDIA) and that is a cloud-based computing facility where we analyze all our data and within an hour of the data being taken, we move it across. That process goes quite quickly depending on how, how large the data set is and then we can immediately reduce and analyze our observations.

So within 24 hours we will know what’s going on. 

Jacinta: [00:24:23] So you need a supercomputer cluster to be able to process all of this data? 

Patrick: [00:24:28] That’s right. 

Dan: [00:24:29] And is this automated or does somebody have to be sitting there? 

Patrick: [00:24:31] It is fairly automated. There are a number of scripts that we can run and that that sort of then takes it in in a semi-automated way.

The goal is to develop this into a fully automated pipeline where we work in near to real-time. To see what’s happening so we can respond in near-to-real time. The optical data gets also transferred from Sutherland in this case, to the same compute infrastructure at the university and there an image gets ingested once it’s completed.

 So every minute at the moment, we’ve got a minute cadence on the optical telescope, a minute repeat timeframe. So at the moment, every new image gets ingested into the database, automatically reduced and that’s then injected into a database of sources all over the sky. 

Dan: [00:25:18] So does the feedback work the other way around too? If MeerLicht observes something that’s transient does it tell MeerKAT?

Patrick: [00:25:25] Eventually, yes, at the moment we are still testing out our transient detection algorithm on the MeerLICHT in the optical sky. Uh, you have to be careful for what’s called false positives and they can be artefacts in the data analysis that might look like a transient, but in fact, it’s, it’s an artefact of the data reduction.

And you have to be very careful not to issue false alerts. But eventually once that is working and once we’re finding transients in the optical database, we would like it and in some cases to feed that back to MeerKAT, but that needs to go through a program, maybe a ThunderKAT program where we have a target of opportunity where we can point the MeerKAT telescope and, but if a transient is occurring in the field, in the MeerLICHT of data, we most likely will have MeerKAT data on that field because the two telescopes are tied together in that sense.

So we should be able to see what’s going on in the radio at the time where we see an optical. 

Jacinta: [00:26:22] And that’s really impressive that you’ve essentially attached this optical telescope to the radio and it tracks exactly the same position as whatever the radio telescope’s looking at at that moment. Has this been done before?

Patrick: [00:26:34] Not, not as far as I know. So the unusual thing here is that the MeerKAT telescope has a very large field of view, which is great for finding new transients. It increases your probability of finding something in the field of view because you just looking at a much larger field of view. But traditionally optical telescopes have a much smaller field of view.

So to match that MeerKAT field of view, which is typically one square degree of the sky. So imagine a grid of two by two full moons together to match that in the optical. We needed to design a wide-field camera that is both a simplistic and operation for robotic operation as well as giving you that wide field of view.

And so the design then led to the MeerLICHT concept, which has a single electronic camera underneath. With 110 million pixels, which can be read out in seven seconds. So, it’s a lot of pixels can be read out in seven seconds. So we take an image of the sky every minute and then seven seconds later we can take our next image.

The data flow from that is, it’s not too high. Although you mentioned earlier, the ThunderKAT data flows is quite large, at the moment it’s about a hundred gigabytes for every one hour of observation and that’s in the low time resolution, a low-frequency resolution that can easily be up to a factor of 30 more.

Jacinta: [00:28:02] I imagine that because you have, it has to have such a wide field of view to match MeerKAT. You’d have to have some sort of trade-off? Probably sensitivity? 

Patrick: [00:28:11] Yeah, so, so we can do the optical design of the telescope that that simultaneously has that wide field of view. You optimize very quickly to a telescope size of about 0.6/0.7 meters.

So that’s smallish for an optical telescope. But within a minute of observation, we’d reached down to a magnitude of 21. 21st magnitude, for point sources for star-like sources, which is at this stage, the optimal limit for a spectroscopic follow up on SALT. The bigger the telescope, the more sensitive.

But with our current design within the minute we, we basically have an optimal follow-up for SALT and we can reach a very faint level of brightness. 

Jacinta: [00:28:52] Okay. It’s got a pretty good sensitivity, or I guess brightness limit, which is the equivalent word in optical astronomy. Not radio. So this is going to say there was something seen with MeerKAT we saw at the same time in the optical. This is an interesting thing. Now let’s go and look at it again with SALT, which is a more sensitive, bigger telescope, right? 

Dan: [00:29:13]  So you seem to be pretty well set up to detect these transients and we, I mean, we were just chatting earlier about one you’ve detected and you have detected a few now with MeerKAT, we really are expecting some new discoveries. There are things we can’t expect to find. In your mind and in the field of transients, what are you expecting? What is exciting with MeerKAT? 

Patrick: [00:29:37] The exciting thing in time domain astronomy is to look at things that vary on very short timescales. I think over the last 10,20,30 years, we very well characterize things that vary on a timescale of days or weeks or months. The Nova explosion, the Thermonuclear explosion on the white dwarf that I mentioned earlier, those are fairly well studied, but we know very little about how the objects in the night sky vary on timescales, less than a day on time scales of an hour or a minute or even below a second.

There’s very exciting objects called fast radio bursts and that gives you a single pulse of maybe 10 milliseconds in, in time that comes from cosmological distances in galaxies, far, far away and we want to characterize those sources. We are now discovering, astronomers are now discovering these in quite large numbers, but still with fairly poor localization in the sky, although that’s getting better.

So one of the things that MeerKAT and MeerLicht can do is to identify and locate them, but also locate the optical counterpart to those fast radio bursts, the host galaxy in which these things reside. These are once-off events if you’re not on the sky when, when this happens, you would have missed it. So by having the wide field of view, you have a greater probability of finding these things 

Dan: [00:30:57] and nobody has observed that yet?

Patrick: [00:30:59] Some have been observed some of these systems are repeating sources and we don’t quite know why. Some are repeating and some are not repeating. But for some of the repeating fast radio bursts, they have been localized quite well and there are host galaxies associated with them. 

Jacinta: [00:31:14] Well, we have so many questions about transients because we know so little about it and we can talk about it all day, but I know you’re a busy person.

We have to let you go soon. Before that, I’d like to just talk about the University of Cape Town Department of Astronomy because it’s celebrating a special anniversary this year. 

Patrick: [00:31:28] That’s right. Thanks, Jacinta for asking that. This year, it’s our 50th anniversary of the astronomy department at the University of Cape Town. It was established in 1970 as a formal department,  versus astronomy departments around the world which actually are part of a physics department. Ours grew out of the physics department at UCT the director of the observatory in Cape Town was an honorary professor of astronomy in the department of physics. But at the time when the observatory changed into the South African Astronomical Observatory and the Sutherland Observatory was being established in the Northern Cape in South Africa and the University of Cape Town decided that it was time to set up its own department of astronomy, which is now 50 years ago. So we’ve, we’ve been doing great astronomy in the last 50 years and there’s a lot of excitement, of course with SALT and MeerKAT to look forward to and we’re celebrating this wonderful milestone with a lot of activities, public talks, outreach events and so on.

Jacinta: [00:32:30] And I’m a part of the current generation there as a postdoc at UCT, are there any of the celebration events that some of our listeners, particularly those in Cape Town can participate in? 

Patrick: [00:32:40] We’ve had a number of things already. We had a public talk by the president of the International Astronomical Union recently.

But throughout the year, we’ll host a number of talks and events. We will advertise them on our website and on our Facebook site as well. We will post them to the public and given the close history that our department has with the South African Astronomical Observatory who is also celebrating a major milestone this year. We will see how to coordinate the 200 anniversary of the SAAO with activities around the 50th anniversary of the Astronomy Department. 

Jacinta: [00:33:11] Oh, great. Well, Dan’s sitting right next to you and he’s running those

Dan: [00:33:15] Patrick and I have spoken already

Jacinta: [00:33:17] Okay.  

Dan: [00:33:19] we’ve, we’ve come up with some ideas which we will implement.

Jacinta: [00:33:22] And Patrick, are there any significant moments that happened in the last 50 years of the UCT Astronomy Department?

Patrick: [00:33:30] Sure. That’s a, that’s a big question. 

Dan: [00:33:33] Well, at least what you can remember. 

Jacinta: [00:33:36] Well, you gave a really great talk at the start of the year about the history of the department and there were quite a few 

Patrick: [00:33:42] there. Lots of wonderful milestones. So we, we’ve had great people, great students coming through the department, people who’ve gone on to find significant posts across the country, across the globe in astronomy.

In terms of the work that we’ve been doing over the last 50 years. It’s quite interesting to see that the astronomy department started with, in 1970 was searching for supernovae and galaxies and studying compact binaries and the astrophysics of these cataclysmic variables that a lot of new insight has been gained in those, in those areas and that the astronomy department is still doing a lot of work in these areas, particularly, I think the highlight has been the inclusion of radio astronomy over the last 15 years with, with MeerKAT on the horizon. We’ve become specialized in radio astronomy, both in the stellar astrophysics side, but also in extra-galactic astronomy. The study of neutral hydrogen, for instance, is one of the strengths in the department I’m very proud of. 

Jacinta: [00:34:41] Awesome and just lastly, before we let you go, are there any other final messages you have for listeners. 

Patrick: [00:34:47] So, so one of the things that’s happened in the astronomy department over the last 15 years, since 2006, is that we restarted our major in astrophysics and that’s grown and grown.

And this year we have 25 3rd year students which is the largest group that we’ve ever had and we organize open days and so my message, to people who are out there who consider a career in astronomy is be curious, be inspired by what goes on in the sky. There’s a lot of things still to discover.

MeerKAT is a fantastic machine, so for the next generation of astronomers in South Africa and the learners at schools, if you want to know what the Universe is made out of you’re in the right place to come and study that. 

Dan: [00:35:30] Great. Thank you very much for joining us, Patrick. We really appreciate your time.

Jacinta: [00:35:34] Thanks, Patrick. 

Patrick: [00:35:35] Great pleasure. 

Jacinta: [00:35:35] Talk to you again soon. 

Dan: [00:35:37] Thank you. When you make another discovery

Jacinta: [00:35:49] All right. I think this concept of MeerLicht is very, very cool to have an optical telescope that’s essentially attached to the radio telescope so that it’s looking at the same place as the radio telescope at all times. 

Dan: [00:36:02] Yeah, I, I mean, we’ve talked about ThunderKAT, that awesome discovery, there’s going to be a lot more from MeerKAT, but getting more and more wavelengths involved yeah and I think it’s just going to be another fascinating avenue of astronomy to go down. So the MeerLicht telescope is, is definitely gonna make some awesome discoveries and contribute to, to some of the discoveries we’ve already made. You know, a very, very exciting project. Very cool and as you said, the first time that this has been done somewhere in the world.

Jacinta: [00:36:31] Yeah, because usually, one telescope in one particular wavelength will spot an interesting object and then send out an alert to all other telescopes, which will then look at it. But in the time it takes for that alert to be made, the transient occurrence may already be finished. So it’s really great that you can have at exactly the same time, both radio and optical observations.

Dan: Yeah, you should note that sometimes those alerts go out in seconds

Jacinta: Sure. Yeah. 

Dan: [00:36:58] and telescopes, can follow up, but the seconds are sometimes not enough for these transients. 

Jacinta: [00:37:03] Yeah, exactly. All right. I guess so the 50th-anniversary celebrations of UCT and the 200th-anniversary celebrations of the observatory, is that going to be, I guess that’s going to be impacted a bit by this Coronavirus lockdown?

Dan: [00:37:19] Yeah, for sure. So we’re not really sure how this is going to go and where we’ll be in October most of the celebration were planned, but at the moment we are talking about various contingency plans, potential postponements, we planned a large astronomy festival. First of all, we are looking at maybe doing it virtually, which will be quite cool actually.

It’s definitely concerning, but the least of our worries right now, I think everyone’s health is is a bigger concern and trying to keep safe. 

Jacinta: [00:37:48] Yeah, exactly. Everyone’s health and safety is by far top priority. 

Dan: [00:37:53] Yes. Keep safe out there guys

Jacinta: [00:37:55] Yeah. Wash your hands, keep social distancing. You know the deal. All right. Good luck everybody and we’ll hope to chat to you again soon.

Dan: All right. See you later. 

Jacinta: Okay. Dan’s logged off Skype, so that leaves me to do the credits. Thank you very much for listening and I hope you’ll join us again for the next episode of the cosmic Savannah. You can visit our website, thecosmicsavannah.com where we’ll have links related to today’s episode.

You can follow us on Twitter, Facebook and Instagram @cosmicsavannah. That’s Savannah spelled S. A. V. A. N. N. A. H. Special thanks today to Professor Patrick Woudt for speaking with us. Thanks to Mark Allnut for music production, Janus Brink for the Astrophotography. Lana Ceraj for graphic design and Thabisa Fikelepi for social media support.

Also to Sumari Hattingh, Brandon Engelbrecht and Lynette Delhaize for transcription assistance. We gratefully acknowledge support from the South African National Research Foundation, the South African Astronomical Observatory and the University of Cape Town Astronomy Department to help keep the podcast running. You can subscribe on Apple Podcasts, Spotify, or wherever you get your podcasts and if you’d like to help us out, please rate and review us and recommend us to a friend. Stay safe everyone and we’ll speak to you next time on The Cosmic Savannah.