World-first linked optical and radio telescopes will capture deep space data
A new optical telescope in Sutherland with a direct link to the just-completed 64-dish MeerKAT radio telescope in Carnarvon, more than 200km away, will be unveiled on Friday.
It will be the first time in the world that a dedicated optical telescope will simultaneously observe the same part of the sky as a radio telescope.
The telescope on the South African Astronomical Observatory’s (SAAO’s) Sutherland site in the Northern Cape is called MeerLICHT, Dutch for "more light".
The site is home to almost two dozen optical telescopes. SA, particularly the Northern Cape, has a geographic advantage in astronomy due to its clear night skies and low population density.
What makes MeerLICHT different from other telescopes, however, is that it will have a direct line to MeerKAT.
"Basically we can visualise in the optical what is being done in the radio," says Patrick Woudt, head of astronomy at the University of Cape Town (UCT) and SA’s principal investigator on the MeerLICHT project.
"People, on an ad-hoc basis, have tried to have the telescopes observing the same portion of the sky at the same time, but the concept of tying telescopes together, that is novel," Woudt says.
The project, six years in the making, is a collaboration between the Netherlands, the UK and SA. It has a price tag of about €1m. Its partner institutions are the Radboud University Nijmegen in the Netherlands, UCT, the Netherlands Organisation for Scientific Research, the SAAO, the University of Oxford, the University of Manchester and the University of Amsterdam, in association with the South African Radio Astronomy Observatory, the European Research Council, and the Netherlands Research School for Astronomy (Nova).
One of its major scientific goals is to track transients across multiple wavelengths. Transient events can occur in the blink of an eye. They are short-lived celestial activity, such as a supernova or gamma-ray burst that can sometimes last a matter of seconds, sometimes days. When those events are picked up by radio telescopes, astronomers on the ground scramble to co-ordinate to look at it with other telescopes.
But when MeerKAT observes these transients, 200km away MeerLICHT will be looking at the same portion of the sky at the same time. The optical telescope is robotic, and so will be able to automatically track MeerKAT’s gaze.
MeerLICHT will take a picture of the MeerKAT radio sky every minute. That data will be transferred immediately to the cloud-based facilities at the Inter-University Institute for Data Intensive Astronomy (Idia).
Established in 2015, Idia is a R10m collaboration between the universities of Cape Town, Pretoria, North West and the Western Cape.
One of the institute’s aims is to make the country’s deluge of astronomy data available to local and foreign scientists.
"By exclusively linking MeerLICHT to MeerKAT we will, for the first time, provide dedicated optical multiband observations of every night-time observation conducted by a radio telescope for the full period of MeerKAT science operations," the project says. "Every transient in the field of view of MeerKAT will be simultaneously covered in the radio and the optical [telescope]," it says.
Other scientists are also keen to see what science the MeerKAT-MeerLICHT link will produce.
"In general, it’s scientifically promising for certain classes of transients," says Tony Beasley, head of the National Radio Astronomy Observatory in the US. The observatory has not been involved in the project.
"Standalone, MeerLICHT will make scientific discoveries — and in combination with MeerKAT, new multiwavelength interests will arise," Beasley says.
MeerKAT, whose 64 dishes were completed earlier in 2018, will ultimately be rolled into phase one of the Square Kilometre Array (SKA). When it is complete, the SKA, will be the world’s largest radio telescope, with dishes and antennas in both Africa and Australia and a total receiving area of 1km².
It will be 50 times more sensitive than current telescopes and will look to answer some of science’s enigmatic questions: are we alone in the universe, what is dark matter, and what happened just after the big bang?
Phase one of the SKA, construction for which is expected to commence in 2020, will include MeerKAT’s 64 dishes and see the addition of about 130 more dishes.
Until then MeerKAT, which was designed and built by SA, will run independently.
SA had so far spent more than R3bn on the MeerKAT and associated human capital development projects, Science and Technology Minister Mmamoloko Kubayi-Ngubane told Parliament ahead of her budget vote earlier in May.
The SKA site, about 80km from Carnarvon, has also been declared a national key point.
SA has spent more than R4.4bn on the SKA project so far, according to DefenceWeb, with some of that money going to acquiring farms around the site to allow for its expansion.