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 ecological areas regions, the park supports a range of animal species, including over 360 bird species. On the lower slopes of Doi Inthanon, near the Karen hill tribe village, Ban Sop Had, are the Wachirathan waterfalls (), where the Wachirathan (lit. "Diamond Creek") tumbles over a granite escarpment. The climate is typically tropical and fairly cool on the summit of Doi Inthanon. In winter the average temperature is 6 °C (43 °F) in January and temperatures can sometimes drop below 0 °C (32 °F). On 21 December 2017, an all-time low temperature of minus-5 °C was recorded at 06:30 at