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MeerLICHT will automatically point in the same direction as the MeerKAT radio array.

Raymond Rutting

Automated telescope to help identify fast radio bursts

A new Dutch telescope is set to help solve a nagging astrophysical mystery, by automatically scanning the southern skies alongside a giant array of radio dishes. MeerLICHT, a 65-centimeter optical telescope, is expected to help identify the sources of fast radio bursts (FRBs)—extremely brief, energetic flashes of radio waves from remote galaxies. In early April, after finishing tests at Radboud University in Nijmegen, the Netherlands, the telescope will be put in crates and shipped via cargo plane to the South African Astronomical Observatory near Sutherland. “We expect to be fully operational in July or August,” says MeerLICHT Project Manager Steven Bloemen.

Astronomers estimate that every day, thousands of FRBs occur around the universe. They last for a fraction of a second and contain as much energy as the daily output of the sun. Yet only a few dozen have been detected so far, by chance, when large radio dishes happened to be pointing in the right direction. In one case, the FRB repeated, which meant other telescopes could make follow-up observations. One favored explanation is that FRBs come from dense, highly magnetized neutron stars in remote galaxies, but their true nature remains pretty much unknown.

MeerLICHT (Dutch for “more light”) may uncover their identity by looking for optical counterparts—transient flashes of light that could help astronomers determine the location and energy of FRBs. MeerLICHT will automatically and continuously scan the same region of sky as the South African radio observatory MeerKAT, which is an array of dozens of 13-meter dishes some 250 kilometers north of Sutherland. “No one has tried this approach before,” Bloemen says.

The €600,000 telescope is designed around an off-the-shelf charge-coupled device (CCD) detector that permits a large field of view, comparable to that of MeerKAT, and more than three times as wide as the full moon. MeerLICHT’s operations will be automated and the telescope will be mostly controlled from Nijmegen. Apart from FRB counterparts, MeerLICHT is expected to detect many other optical transients, such as supernovae.

MeerLICHT is also the prototype for BlackGEM—another automated telescope project led by Radboud that will be constructed in Chile in 2018. BlackGEM is going to hunt down optical counterparts of sources of gravitational waves—tiny ripples in spacetime generated by colliding black holes and neutron stars and detected for the first time in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO). Depending on future funding, the initial BlackGEM array of three 65-centimeter telescopes may be expanded to five or even to 15 instruments in the years to come. According to Principal Investigator Paul Groot, also from Radboud University, “BlackGEM is the only large observatory that will be fully dedicated to counterpart searches of new discoveries by LIGO.”