The Thai National Observatory (TNO) is NARIT's main facility, atop Thailand's highest mountain, Doi Inthanon in Doi Inthanon National Park, Chom Thong District, Chiang Mai Province. In 2020, NARIT completed the construction of the Thai National Radio Telescope (TNRT), a 40m single-dish short-millimetre telescope in Huai Hong Khrai Royal Development Study Centre at Doi Saket District in Chiang Mai Province.