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Completion of CCAT-prime telescope in sight

Decisive advances have been made in the assembly of the long-planned submillimetre wavelength telescope as well as in construction work at its future site in the Chilean Atacama Desert / The project team now anticipates the start of its operations in the second half of next year

The foundation for the Fred Young Submillimeter Telescope at the summit of Cerro Chajnantor. Copyright: CCAT Observatory Inc.

The construction of the Fred Young Submillimeter Telescope (FYST), developed by CCAT Observatory Inc., an international scientific consortium with a 25 per cent participation from the Universities of Cologne and Bonn, has taken several decisive steps towards completion.

The FYST, also known as CCAT-prime (Cherro Chajnantor Atacama Telescope-prime), will have a 6-metre mirror diameter, and is designed to operate at submillimetre to millimetre wavelengths. It will be located at 5,600 metres elevation on Cerro Chajnantor in Chile, overlooking the ALMA array. The novel optical design of FYST will deliver a high-throughput, wide-field of view telescope capable of mapping the sky very rapidly and efficiently.

Work is poised to begin on a defining feature of the telescope, the “elevation” part that supports the upper structure and will contain the telescope’s mirrors. Unlike almost any other telescope to date, the part will be constructed from Invar, a special formulation of steel that has an extremely low coefficient of thermal expansion.

“This means that it doesn't get bigger when it's hot and it doesn’t shrink when it's cold,” said project manager Jim Blair from international project partner Cornell University. “At least, it’s greatly, greatly reduced with Invar compared to regular steel. And that's important for the science because at the wavelengths that we are looking at, thermal expansion would actually affect the data and could ruin it.”

Thus, said Blair, the FYST “will be able to look regularly at wavelength ranges very few other telescopes can even detect because of some of these design elements and material choices.” The telescope’s mirrors are also cutting-edge technology, said Blair. They are being built in the Netherlands by Airborne, one of the world’s premier carbon fibre companies.

The internal steel skeletal structures for two of the yoke arms, which will hold the three-story tall elevation part in place, are almost complete; once the elevation part is finished, all these massive sections will be mounted on top of the already completed lower portions and the telescope will be nearly assembled. The project team estimates that by the end of 2023, they will begin to test the telescope in Germany.

The proximity of the trial assembly site at Wessel GmbH in Xanten, Germany to the University of Cologne, a CCAT-prime partner, permits quick site visits and interaction with staff at Vertex Antennentechnik GmbH of Duisburg, Germany, the company designing the telescope.

“This allows us to have close cooperation with the constructor and follow in detail the finer points of the telescope development right down to the power socket locations,” said Dr Ronan Higgins, CCAT-prime deputy project engineer at the University of Cologne’s Institute of Astrophysics. “I have travelled back and forth over the roads of the region following subassemblies from different suppliers. You appreciate what a massive effort it is to bring this telescope together and how many unseen people work in the background to bring all this together.”

The CCAT-prime observatory offers a number of projects for doctoral student development, not only in astronomical research, but also in telescope commissioning, for example the mirror panel alignment holography. “I have worked the last 3 years on the holography system development at the University of Cologne’s Institute of Astrophysics, we’ve successfully tested the system in the lab to a precision of 2 micron and look forward to bringing this system to the telescope in 2023,” said doctoral candidate Xiaodong Ren.

Because of the extreme altitude of the FYST summit site on Cerro Chajnantor located in the Andes mountains of Chile – it will be the second highest telescope in the world, the highest being only fifty meters beyond it at the summit of the mountain – the entire telescope is being constructed and pre-assembled in Germany, and will be disassembled into about 12 major sections and transported to Chile for reassembly. This major undertaking is anticipated in 2024. The transport will be orchestrated by Vertex and is expected to take four months or longer.

In Chile, major work has been accomplished in recent months by Chilean contractor Consorcio FVV Ingeniería y Construcción Limitada. The nine-kilometre trench running from the base camp at an altitude of 5,000 metres, where the observatory’s power generation system will be located to the mountain summit, carrying the main power cable and fibre optic cable for data, is complete.

Work at the telescope site at 5,600 metres elevation is complicated by the extreme altitude. Workers have to be trained and pass an exam to be registered to work at that height, and can work a maximum of 12 to 13 days at a time. For each day they work at extreme altitude, members of the 108-person construction crew must spend a day below at approximately 2,700 metres.

A final project this spring will be a concrete container for an 80,000 litre fuel tank, to ensure that any possible fuel leak will not harm the environment. The containment will be one and half times the size of the fuel tank, explained Blair, so that it will not overflow in case of snow or rain.

The main power generators, already procured, and the electronics cabinets, switchgear and transformers will be the last components installed at the base facility before the telescope itself arrives for installation at the summit. This work is projected to start in the third quarter of 2023, with the power system commissioned by early 2024, if not before.

“This project is a major undertaking, about the largest that can be lifted by a consortium of research universities”, said Professor Dr Dominik Riechers, who leads the group for submillimetre astronomy at the University of Cologne’s Institute of Astrophysics. “We have several tens of students at bachelor’s and master’s level, research scientists and engineers involved in this project here in Cologne, who work in our highly specialized workshops and laboratories to make this project a reality. We are all very much looking forward to using this extraordinary facility in 2024 and for many years to come.”


Media Contact:
Dr Isabelle Breloy
Institute of Astrophysics, University of Cologne

Press and Communications Team:
Eva Schissler +49 221 470 4030


Further information:
CCAT Observatory
CRC 956 (2011-2022) Conditions and Impact of Star Formation - Astrophysics, Instrumentation and Laboratory Research