WoU-MMA: Development of the Optical Alignment Systems for the Medium-Sized Telescopes of the Cherenkov Telescope Array

The Cherenkov Telescope Array Observatory (CTAO) is a forthcoming state-of-the-art facility to study very high-energy gamma-rays and provide transformative understanding of the most extreme objects in the Universe, including pulsars, supernova remnants, gamma-ray bursts, and supermassive black holes at the center of active galaxies. The CTAO is now entering the construction phase of the project, with first science observations anticipated in approximately three years utilizing the first pathfinder imaging atmospheric Cherenkov telescopes (IACTs) of the observatory.

This award supports U.S. CTAO scientists in the development, fabrication, and installation of the optical alignment systems for the initial seven medium-sized CTA telescopes, including five at the northern site at Rogue de los Muchachos Observatory, La Palma, Spain, one at the southern site at the European Southern Observatory, Paranal, Chile, and the prototype Schwarzchild-Couder telescope (pSCT) located at the Fred Lawrence Whipple Observatory in Arizona.

The awarded activities provide a unique instrumentation training ground for students and early career researchers and a series of workshops are planned to develop educational high-energy astrophysics materials for K-12 schools. The leading U.S. contributions provided via this award provide the foundation for broad access of U.S. scientists to CTAO and the next generation gamma-ray discoveries.

The CTAO will utilize advanced IACT technology in large arrays of three telescope apertures: large (23m), medium (10-12m) and small (4m). The medium-scale telescopes targeted in this award involve a single-mirror, prime focus Davis-Cotton design and a double-mirror, aplanatic Schwarzschild-Couder design. The observatory will provide up to ten times increased sensitivity over current instruments in measurements of astrophysical gamma-rays at energies between 20 GeV – 300 TeV.

With design improvements of a 3x increase in imaging area, the CTAO will enable astrophysical sky surveys to be completed approximately 300x faster than current facilities, revolutionizing high-energy gamma-ray follow-up to multi-messenger astrophysics events, including those triggered by gravitational wave and high-energy neutrino alerts. The initial five medium telescopes at the northern site will be the most sensitive array in their energy-band as a stand-alone instrument.

Operating in conjunction with the four large-sized telescopes currently being built on the site will form the largest, most sensitivity array of IACTs yet assembled. The first medium-sized telescope to be outfitted at the southern site will be the first IACT in the southern portion of the Western hemisphere, providing important new sky coverage for transient events such as gravitational wave counterparts.

Finally, the high-angular resolution of the novel pSCT design will provide unique future additional reach to the CTAO program. This project advances the goals of the NSF Windows on the Universe Big Idea.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.