The MeerLICHT instrument in Sutherland will be specifically linked to the MeerKAT radio telescope array near Carnarvon in the Northern Cape.

Unlike its bigger brother SALT (Southern African Large Telescope), the MeerLICHT is meant to give astronomers a large field of view and match observations with the MeerKAT.

While SALT conducts spectroscopy - analysing light in different segments - MeerLICHT conducts all its investigations in the visible light spectrum.

MeerKAT conducts its investigations in the radio frequency spectrum, enabling scientists to examine the cosmos in greater detail than optical telescopes might allow.

Puzzling phenomenon

"MeerKAT has a very large field of view and once MeerKAT starts science observations, we will be searching the entire field of view all the time for new transients," MeerLICHT principal investigator Professor Patrick Woudt told News24.

"We don't know beforehand where such objects will appear in the large field of view and so it is necessary to cover the same field of view in the optical (at the same time) if we want to identify an optical counterpart to a newly-detected radio transients," said Woudt, head of the astronomy department at UCT.

He said that the MeerLICHT may help astronomers understand the puzzling phenomenon of fast radio bursts (FRBs).

These appear suddenly and disappear within 100 milliseconds, making it difficult to examine them thoroughly.

"We don't really know what they are, other than that they must be very distant objects. As a rule, they only appear once (only one of them has been shown to repeat these bursts).

"By matching the optical camera's field of view to that of MeerKAT, we can instantly identify a counterpart in the optical to these fast radio bursts, even if they occur by chance at the edge of our viewing window," said Woudt.

Richard Lieu, in The Astrophysics Journal, wrote that the discovery of FRBs could lead to a re-examination of phenomena such as pulsars.

Other researchers argue that FRBs could be related to super powerful magnetic stars known as magnetars.

Massive images

MeerLICHT is a completely robotic instrument and, at 110 million pixels, is the largest scientific CCD camera that can be made, said Woudt.

In a top-end smartphone, a 20-megapixel camera can produce a 2.45MB compressed image, and at 110 megapixels, a compressed image could come in at 22MB.

The uncompressed images from the MeerLICHT, however, come in at 350MB, include positional data and up to one million stars per image, making for superb study data.

The cost of the camera alone contributed 20% to the cost of the entire instrument.

"Our optical camera needs to be cooled to similar temperatures as the SALT optical detector. This is done with liquid helium at temperatures around 80 Kelvin (-193°C) in a constant cooling cycle.

"Another novelty of MeerLICHT is that we put all our electronics in the counterweight of the telescope and take the excess heat of the electronics away with water cooling. This way we keep the excess heat (and source of turbulent air) away from the optics, leading to sharper images," Woudt explained.

The total cost for the instrument is €1m (about R14.55m) and it will be permanently linked to the MeerKAT radio telescope.

"The telescope optics design needed special considerations to achieve the large field of view matching that of MeerKAT across a flat focal plane; this contributed to the cost," said Woudt.

The MeerLICHT will receive its pointing data from the MeerKAT and will be launched with partners from the UK and Netherlands.

News24