/ 30 March 2016

New telescope MeerLicht to observe transients

Sutherland is blessed with very little light pollution
Sutherland is blessed with very little light pollution

It can happen in the blink of an eye: millions of light years away a star collapses in on itself. From Earth, that cataclysmic event is only a sudden brightening of a point in the night sky, and on the ground, astronomers scramble to investigate it.

A new telescope, to be installed at South Africa’s Sutherland astronomy site in the next year, will catch these faint flickerings, among others, and help us understand more about what is happening in the universe.

But what makes it different from other optical telescopes observing these transient astronomical phenomena in Sutherland is that the MeerLicht (“more light” in Dutch) telescope will be linked directly to South Africa’s MeerKAT radio telescope, more than 200km away.

“This is a novel way of doing things – creating a real-time link with optical and radio telescopes,” says Patrick Woudt, head of astronomy at the University of Cape Town and South Africa’s principal investigator on the MeerLicht project.

MeerKAT, designed and built in South Africa, will comprise 64 dishes and be incorporated into the Square Kilometre Array (SKA). The SKA will be the largest radio telescope in the world ­– and the largest scientific instrument on Earth – with antennas in Africa and Australia.

MeerKAT’s first 16 dishes are expected to be science-ready in June, and the deadline for the full array will be late next year. The first five years of observing time have already been allocated.

Former SKA South Africa director Bernie Fanaroff once joked that the name “MeerKAT” was Afrikaans for “More KAT”, because KAT-7 – the seven-dish Karoo Array Telescope – was a prototype to show the international community that South Africa was willing and able to host the SKA.

The telescope is a collaboration between South Africa and the Netherlands, specifically the Radboud University of Nijmegen, and will be operational next year.

“Wherever MeerKAT looks, MeerLicht will as well,” he says. MeerKAT will look at radio waves coming from the deepest reaches of space, and MeerLicht will follow its gaze but will look at visible light.

Transients – ‘things that go bump in the night’
The two telescopes will be observing a phenomenon that is gaining increasing attention: transients.

“Transients are things that go bump in the night,” says David Buckley, an astronomer from the South African Astronomical Observatory.

He is sitting in the 1.9m telescope – one of more than 20 telescopes on the Sutherland site, which is known for its astronomy-perfect climate and dark skies.

Transients, otherwise known as transient astronomical events, can include stars dying (supernovae), erupting variable stars, gamma-ray bursts and a host of astronomical phenomena. They can last for seconds or days.

MeerLicht will join an existing South African-Russian programme investigating transients, called Master, which is already installed on the Sutherland site.

“In the past, we’ve had to rely on the notification of the sudden discovery of these things from other observatories, and then follow them up with our facilities here at Sutherland,” says Buckley.

He is the South African principal investigator on the Russian Master programme, a network of telescopes: five in Russia, one in the Canary Islands and one in Sutherland.

“This one here in Sutherland is the only one in the southern hemisphere; it will be joined by one in Argentina at some point,” he says.

But MeerLicht will be a dedicated second set of eyes for MeerKAT, even though it is not actually part of or funded by SKA South Africa.

This project, funded to the tune of about €500 000 and being constructed in the Netherlands, is dovetailing with one of MeerKAT’s large sky surveys. For these surveys a telescope observes large parts of the sky, rather than a specific celestial object.

MeerLicht will shadow the MeerKAT’s ThunderKAT survey, which will trawl the skies for explosive bursts of radio waves.

“There are many things that suddenly become brighter in the radio wavelength,” says Buckley.

“The idea with this optical telescope [MeerLicht] is to point at the same area of sky that MeerKAT is observing, so that we would have simultaneous optical observations for the same thing.”

Asked why the telescope would be located at Sutherland rather than on the Carnarvon site, where MeerKAT will be located, Woudt says that Sutherland, home to national telescopes since the 1970s, “has long experience in running and operating optical telescopes”.