National Astronomical Research Institute of Thailand 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. The concept of a national astronomical research institute was discussed for the first time in the Assembly of the Deans of the Faculty of Science in Thai universities. On July 20, 2004, commemorating His Majesty King Bhumibol's 80th Birthday Anniversary in 2007 and marking the bicentenary of the life and work of King Mongkut the "Father of Thai Science" the government approved the establishment of the National Astronomical Research Institute of Thailand (NARIT), under the
Doi Inthanon at Doi Luang, which was then renamed in his honour. Today, the summit of Doi Inthanon is a popular tourist destination for both foreign and Thai tourists, with a peak of 12,000 visitors visiting the summit on New Year's Day. In addition to a range of tourist facilities on the summit, there is also a Royal Thai Air Force weather radar station at the summit and the Thai National Observatory (TNO) at km44. Doi Inthanon is the highest peak of the Inthanon Range () of the Thanon Thong Chai Range, a subrange of the Shan Hills in the Thai highlands