MeerKAT radio telescope inaugurated in South Africa – reveals clearest view yet of the centre of the Milky Way galaxy
SARAO celebrates the successful completion of the SKA Telescope Manager Critical Design Review
The General Assembly of the International Astronomical Union to be hosted on African soil for the first time in 2024
SKA in South Africa was highlighted during the Chinese State visit – identified as vehicle for diplomacy and development
Minister Pandor opens new road to Losberg site, meets with residents of Carnarvon and surrounding communities
US Embassy members visit Losberg and Carnarvon
European Union delegation visits SARAO Cape Town office
First cohort of SARAO-sponsored Northern Cape matrics progressing well at university
2017 SARAO bursary beneficiaries progress to second year of tertiary studies
Students from African countries complete third HartRAO AVN training school
Public participation process underway for the development of the Park Management Plan for the new proposed National Park in the Karoo
MeerLICHT telescope inaugurated
SARAO hosts Minister Kubayi-Ngubane and members of Parliamentary Portfolio Committee at Losberg
SARAO hosts Community Information sessions in the Northern Cape
South Africa’s initialling of the SKA Convention and Protocol texts takes place in Rome, Italy
Astronomy in South Africa is profiled at the IAU GA 2018 in Vienna
SARAO staff member leads 2018 NRAO NINE Program
Dr Bernie Fanaroff acknowledged by National Research Foundation by Lifetime Achievement Award at NRF Awards 2018
HartRAO instrumental in the successful adoption of the Third realisation of International Celestial Reference Frame (ICRF-3)
Chinese Vice Minister for Science and Technology visits SARAO offices
Ghana and South Africa celebrate first success of African network of telescopes
Joint media statement on the outcomes of the 5th Ministerial Meeting of the Square Kilometre Array African Partner Countries
Breakthrough Listen to incorporate the MeerKAT array in its existing search for extraterrestrial signals and technosignatures
Servitude establishment program
Latest developments on the land acquisitions programme
SARAO Human Capital Development Programme – Creating excellence in radio astronomy
SARAO Tech News
MeerKAT radio telescope observes a rare burst of activity from an exotic star, demonstrating outstanding capabilities as a new instrument for scientific exploration
Ghana marks first spot on the AVN
Standing on the shoulders of giants: a South African’s contribution to global radio astronomy
HERA: Building to view the past
Across the Globe
SKA prototype dish assembled for the first time
First SKA-Low Prototype Station completed on site
SKA precursor upgrade makes telescope 10 times more powerful
Paving the way towards the SKA: astronomers detect signal from the first stars
Spain joins the SKA Organisation
New platform to showcase SKA’s major engineering progress
SKA treaty open for initialling
SARAO Science Engagement
RD9 Solutions: Introduction to Robotics
DST Mini Science Forum ignites conversations about big science
SARAO participates in Science Centre World Summit 2017
SARAO participates in third Science Forum South Africa
SARAO/SKA SA hosts DST Mini Science Forum in Northern Cape
Scifest Africa 2018
SARAO and Oculus announce partnership
SARAO wins Best Workshop prize at Scifest Africa 2018
NASA Electrical Engineer visits schools in Sutherland
SARAO participates in Public Communication of Science and Technology Conference in Dunedin, New Zealand
Participants graduate from Phase 1 of MAPPP NINE
SKA AVN MAPPP NINE Development Lab
MAPPP NINE expands to SKA AVN
IAU CAP 2018
SARAO participates in EuroScience Open Forum 2018 in Toulouse, France
National Science Week 2018
SARAO hosts 2018 SAASTA National Schools Debates Competition in the Northern Cape and North West
SARAO Big Data Africa School 2018 kicks off
Carnarvon High School teams through to National Competition of World Robot Olympiad 2018
SARAO Big Data Africa School 2018 ends on high note for African students
SARAO staffers shine at INCOSE SA 2018 conference
Five SARAO electrician trade artisan students attend media training in Carnarvon
SARAO Junior engineer wins Best Poster Presentation at UCT Engineering Research Expo
Dr Bonita de Swardt presents at plenary session at Grand Challenges Partners meeting in Kenya
SARAO bursary holder wins first prize in AT-RASC student paper competition
Dr Aletha de Witt elected to the IAU commission on astrometry
Dr Rob Adam inducted as a Fellow of the South African Academy of Engineering
SARAO bursary funded students selected for 2018/19 CSIRO scholarship
Junior Science Process Developer wins Thomson Reuters Award
Brendan Swarts – Electrician Artisan student
Morgan Daba – Electrician Artisan student
Marthinus Steyn – Telescope Operator
Griet Tobias – Housekeeper
Jan Mouers – General Worker
Mathakane Molewa – HERA Construction Supervisor
Malissa Pietersen – Procurement Officer (Site)
Lourencia Lyon – HERA General Worker
Peter van Wyngaarden – HERA General Worker
Bradwin Vermeulen – HERA General Worker
Tyrone Adams – HERA General Worker
Levurd Vaarland – HERA General Worker
R. Sean Oliphant – Mathematics teacher at Carnarvon High School
Standing on the shoulders of giants: a South African’s contribution to global radio astronomy
SARAO News #02 2018
Lerato Sebokolodi doesn’t like being told what to do. This independent thinker nearly left academia for the private sector, until she realised that she would have to dress a certain way, follow instructions and rules, and generally do what other people told her. Her choice to stay was a good thing for the discipline of astrophysics, because now she is doing groundbreaking work on one of the universe’s most-studied objects, a radio galaxy called Cygnus A.
Sebokolodi started her academic career studying physics and mathematics, ultimately hoping to go into geophysics. Then a lecture from visiting astronomer Thebe Medupe piqued her interest in astrophysics while she was completing her BSc.
“He told me what he was working on and I thought it sounded great,” she says. “He gave me an opportunity to attend a winter school, which gave me a much wider exposure to astronomy, and I decided to continue in the field.”
She completed her Honours degree through the National Astrophysics and Space Science Programme (NASSP) at the University of Cape Town (UCT), and then began to think about getting a job.
“I couldn’t see where I would fit in when I started applying for jobs, given my personality. I wanted the freedom to do what I want to do, not to follow instructions. It was so hard to find a job that suited me.”
Fortunately, her Honours project supervisor, introduced her to Prof Oleg Smirnov, SKA Chair in Radio Astronomy Techniques and Technologies at Rhodes University. She joined Smirnov’s team to work on data processing – her Masters degree involved developing an algorithm to determine what is real and not real in radio interferometry images.
“I knew I didn’t have the computer science background, but I wanted to do something new,” says Sebokolodi. “It went well, but by the end I wasn’t sure whether I wanted to continue with software-related work – I had diverged from my initial passion to study physics.”
Her next career step would put her firmly back on track.
A brief history of Cygnus A
In November 2016, Smirnov introduced Sebokolodi to Dr Rick Perley of the National Radio Astronomy Observatory (NRAO), who offered her a PhD working on Cygnus A. She accepted soon after and moved to the USA in August 2017.
Perley has been studying Cygnus A since 1977, when he took up the first ever post-doctoral position at the newly-established Very Large Array (VLA), located on the bed of an ancient lake near Socorro in the New Mexico desert. The VLA is the largest and most powerful radio telescope in the world, and will be until SKA Phase One comes online in 2023.
“The VLA was designed to focus on astrophysics problems of the time – one of these was the puzzle of radio galaxies and quasars,” says Perley. Radio galaxies like Cygnus A show two huge balloons, or lobes, of electromagnetic radiation in the low-energy frequency end of the spectrum – radio waves. These lobes are expelled by certain galaxies, but when the VLA was commissioned, that was about all that could be said about these celestial objects.
“We wanted to know what is fuelling the radio lobes, how did they evolve, what is the content? VLA gave us the sensitivity and resolution to look into the galaxy core, the hotspots, the jets. I chose to look at Cygnus A.”
Cygnus A is the best radio galaxy to study in the Northern hemisphere – it is relatively close and extremely bright, which means we can study it with high spatial resolution and good sensitivity. Not only this, but Cygnus A is highly linearly polarised – a source is polarised if its electromagnetic radiation has a prefered orientation and linear if the waves oscillate in a single direction.
Researchers learned much about the structure and physical characteristics of radio galaxies in general, and Cygnus A in particular, over that time. They now knew that at the centre of Cygnus A is a black hole, which accretes matter as all black holes do. However, some matter is expelled by the black hole as jets of radio energy, and interacts with interstellar medium which in turn creates a shockwave that generates the radio lobes that have been observed for this and other radio galaxies. They also found that at the extremities of the lobes of Cygnus A are two hotspots.
More importantly, they noticed that polarised emissions from Cygnus A, like many other radio galaxies, are rotated during propagation towards Earth. By the early 1990s, after years of observations and research, Perley felt he and his colleagues had found a clear picture of the physics of Cygnus A and its environment, and moved on to other projects.
At this point, it was clear that the matter surrounding Cygnus A causes rotation of polarised emissions. However, researchers could not yet disprove that the observed rotation could be due to thermal emissions inside the radio lobes. Although they were able to measure the polarisation properties of Cygnus A, the measurements could only be made at a few frequencies, and investigating the contents of the lobes was close to impossible.
It would take a technological upgrade of the VLA before researchers could start to shine a light on these mysteries.
Carrying the radio astronomy torch
That upgrade came in the form of a $90 million technology injection into the VLA. Completed in 2012, Perley was closely involved in the process.
“Sometime during the 1990s, I became interested in promoting improvements to the telescope, and headed up the VLA upgrade project,” says Perley. “This has increased its capabilities in virtually every way except for resolution – new receivers, correlators, fibre optics and other technology.”
All of these improvements greatly expanded the possibilities of research on the telescope, known as the Karl G. Jansky Very Large Array (JVLA) since it was recommissioned in 2012. In particular, it meant that Cygnus A could be studied in ways that weren’t previously possible, providing the technical capabilities needed for Sobokolodi’s to do her work.
“The idea of working with people who have worked on Cygnus A for years, that was really appealing,” says Sebokolodi. “I couldn’t refuse the offer.”
Perley invited Sebokolodi to work on data from 44 hours of observations of Cygnus A, across a vastly expanded frequency spectrum – in the 1970s, Perley had collected radio frequency data across just four channels, but now researchers had literally thousands of channels to work with.
He cleaned and calibrated the data, and in August 2017 she moved to the tiny university town of Socorro, New Mexico, to start work in earnest.
Sebokolodi fitted in almost immediately, making friends and filling her days with social activities – no easy task in a town of only 8000 people, way out in the American Midwest.
Perley and Sebokolodi clearly found a good personality match in each other – she wants to be left to her own devices and really get stuck into a problem, and he likes to give his students free rein to solve their own problems, only stepping in occasionally to provide guidance or help them get past obstacles. In just five months since Sebokolodi has been working on Cygnus A, they already have exciting and potentially groundbreaking results.
The wealth of new frequency data has allowed Sebokolodi to revisit previous assumptions about certain characteristics of the radio galaxy. She has detected depolarisation in the radio signals, which indicates that the radio lobes can’t be empty – there must be some gas inside them.
“Lerato recently came back to me with surprising results,” says Perley. “They are not in line with my preconceived ideas about the polarisation structure of Cygnus A, which is a little embarrassing, but also extremely pleasing to me.”
“Overall, we’re very pleased with the progress. I think we’re going to make a pretty big splash when we make the results public.”
The future of radio astronomy is Southern
While these results are set to make waves right now, Sebokolodi is already looking to the future.
“Getting observation time on the SKA will be very competitive, so I have to know what I am talking about,” she explains. “I want to acquire as many skills as possible now. When you write proposals, the reviewers want to see that people involved in the proposal have the correct expertise.”
The SKA is mostly employing engineers and software developers at the moment, because the telescope is still under construction. But a few, like Sebokolodi, are being employed and funded to gain skills in basic science as part of the Young Professionals Development Programme at the SKA.
Sebokolodi says that at first she felt like she wasn’t making a contribution. “But look at the bigger picture – in the future I will be an expert in cluster magnetic fields, radio galaxies, and radio astronomy techniques. There is no better place for me to learn.”
A perfect example of this is the technique she is using to study Cygnus A, known as rotation measurement synthesis; it is a relatively new technique in this field, and she is putting it to novel use.
“Our methods and results will ultimately guide and inform work done at the SKA on similar objects,” explains Perley. “We’re establishing a path, but other people will need to build the roads to get the best out of the technique and the instruments they have.”
Sebokolodi is gracious in her excellence and grateful for the opportunity that has been presented to her.
“My days are spent researching and doing what I want to do. This research project allows me to have my own ideas, to question people’s assumptions, and to contribute to the field. I really am blessed right now.”
Big Data Attendees at the one-day work session which was held on 11 July 2017 at the Ministry of Environment, Science, Technology and Innovation in Ghana to kick off the High Performance Computing training programme in Ghana.
Members of the nine SKA African partner countries concluded the Fourth Ministerial Meeting on the SKA in Accra, Ghana by signing a memorandum of understanding to collaborate on radio astronomy.
Minister of Science and Technology Naledi Pandor watches on as the President of the Republic of Ghana, His Excellency Nana Addo Dankwa Akufo-Addo cuts the ribbon at the launch of the Ghana Radio Astronomy Observatory.
The launch of the Ghana Radio Astronomy Observatory was covered 119 times in the media between 23 and 25 August 2017:
In Ghana: 24 times
In South Africa: 36 times
In other African countries: 8 times
Internationally: 51 times
The value of these placements is R6 983 234.17.
Last Updated on November 19, 2018