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28 January 2021 | Story Igno van Niekerk | Photo Supplied
Pictured from the left: Lucas Erasmus from the Department of Physics, Piet le Roux from the Astronomical Society of SA – Bloemfontein, Quinton Kaplan from the Department of Physics, Thinus van der Merwe from the Astronomical Society of SA – Bloemfontein. Front: Prof Matie Hoffman

In his book, The World is Flat, Thomas Friedman mentions how at first countries, then companies, and eventually communities went global. In true flat-world fashion, a combined team of the University of the Free State (UFS) and the Astronomical Society of South Africa – led by Prof Matie Hoffman, Associate Professor in the Department of Physics – participated in a once-in-a-lifetime event with their counterparts from the Ellinogermaniki Agogi School and the Skinakas Observatory in Greece.

On 21 December 2020, Earth was treated to the Jupiter-Saturn conjunction, when the two planets were only 0.1 degrees apart in the sky. Although conjunctions are regular phenomena, NASA mentions that the great conjunction of Jupiter and Saturn in 2020 was the closest since 1623 and the closest observable since 1226! A pinkie finger at arm’s length could cover both planets – although they were still millions of kilometres apart in space.

Planning started months ahead of the event, with the Ellinogermaniki Agogi Observatory in Greece and the Boyden Observatory in Bloemfontein chosen as the two selected vantage points. From both the Southern and Northern Hemisphere, the conjunction would be broadcast live on YouTube. As with any other technical project on an international scale, challenges arose. For example, in the Northern Hemisphere, it was already dark at 17:45 while the South African astronomers were still basking in sunlight until after 19:00. The conjunction would only be visible from South Africa after 19:30, almost two hours after it would be visible in Athens. The time was well used, with the event including a word of welcome by the Consul General of Greece in South Africa, Ioannis Chatzantonakis, presentations on Saturn and Jupiter, as well as a virtual tour of the Boyden Observatory, emphasising its connection with Greece through its first Director, Stefanos Paraskevopoulos. 

On Saturday, 19 December, the teams ‘gathered’ on opposite sides of planet Earth to do a dry run. One could sense the urgency and tension as both teams realised that they would have a huge captive audience on YouTube, and plans had to be made in case of connectivity challenges and if the weather did not allow the conjunction. As preparations progressed, Prof Hoffman was talking to his Greek counterparts and was simultaneously walking around with his laptop to share the landscape and activities via his webcam with colleagues in Greece. 

Monday 21 December 2020 – the weather prediction was correct. Clouds covered the Free State sky and scattered raindrops started to fall. Revert to Plan B. A recording made on Saturday evening was shared via the YouTube link, while a live feed of the conjunction from elsewhere in South Africa was arranged. From both sides of the world, information was shared about the history of the venues, as well as the marvel of what was happening in space. Fortunately, expert planetary photographer Clyde Foster was able to share a live feed just after 19:30 from the observatory at his home in Centurion, Gauteng. Those attending the event where visuals and speakers were together on one screen – yet thousands of kilometres apart – watching an event in outer space, will indeed agree with Thomas Friedman: the world is flat. The live-stream event of the conjunction was a catalyst that will result in continued collaboration between the UFS and colleagues in Greece in the field of astronomy. 

By the time of this writing, the livestream has reached more than 50 000 people.


News Archive

UFS physicists publish in prestigious Nature journal
2017-10-16

Description: Boyden Observatory gravitational wave event Tags: Boyden Observatory, gravitational wave event, Dr Brian van Soelen, Hélène Szegedi, multi-wavelength astronomy 
Hélène Szegedi and Dr Brian van Soelen are scientists in the
Department of Physics at the University of the Free State.

Photo: Charl Devenish

In August 2017, the Boyden Observatory in Bloemfontein played a major role in obtaining optical observations of one of the biggest discoveries ever made in astrophysics: the detection of an electromagnetic counterpart to a gravitational wave event.
 
An article reporting on this discovery will appear in the prestigious science journal, Nature, in October 2017. Co-authors of the article, Dr Brian van Soelen and Hélène Szegedi, are from the Department of Physics at the University of the Free State (UFS). Both Dr Van Soelen and Szegedi are researching multi-wavelength astronomy.
 
Discovery is the beginning of a new epoch in astronomy
 
Dr van Soelen said: “These observations and this discovery are the beginning of a new epoch in astronomy. We are now able to not only undertake multi-wavelength observations over the whole electromagnetic spectrum (radio up to gamma-rays) but have now been able to observe the same source in both electromagnetic and gravitational waves.”
 
Until recently it was only possible to observe the universe using light obtained from astronomical sources. This all changed in February 2016 when LIGO (Laser Interferometer Gravitational-Wave Observatory) stated that for the first time they had detected gravitational waves on 14 September 2015 from the merger of two black holes. Since then, LIGO has announced the detection of two more such mergers. A fourth was just reported (27 September 2017), which was the first detected by both LIGO and Virgo. However, despite the huge amount of energy released in these processes, none of this is detectable as radiation in any part of the electromagnetic spectrum. Since the first LIGO detection astronomers have been searching for possible electromagnetic counterparts to gravitational wave detections. 
 
Large international collaboration of astronomers rushed to observe source
 
On 17 August 2017 LIGO and Virgo detected the first ever gravitational waves resulting from the merger of two neutron stars. Neutron star mergers produce massive explosions called kilonovae which will produce a specific electromagnetic signature. After the detection of the gravitational wave, telescopes around the world started searching for the optical counterpart, and it was discovered to be located in an elliptical galaxy, NGC4993, 130 million light years away. A large international collaboration of astronomers, including Dr Van Soelen and Szegedi, rushed to observe this source.
 
At the Boyden Observatory, Dr Van Soelen and Szegedi used the Boyden 1.5-m optical telescope to observe the source in the early evening, from 18 to 21 August. The observations obtained at Boyden Observatory, combined with observations from telescopes in Chile and Hawaii, confirmed that this was the first-ever detection of an electromagnetic counterpart to a gravitational wave event. Combined with the detection of gamma-rays with the Fermi-LAT telescope, this also confirms that neutron star mergers are responsible for short gamma-ray bursts.  
 
The results from these optical observations are reported in A kilonova as the electromagnetic counterpart to a gravitational-wave source published in Nature in October 2017.
 
“Our paper is one of a few that will be submitted by different groups that will report on this discovery, including a large LIGO-Virgo paper summarising all observations. The main results from our paper were obtained through the New Technology Telescope, the GROND system, and the Pan-STARRS system. The Boyden observations helped to obtain extra observations during the first 72 hours which showed that the light of the source decreased much quicker than was expected for supernova, classifying this source as a kilonova,” Dr Van Soelen said.

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