The Indian Astronomical Observatory (IAO) is a high-altitude astronomy station located in Hanle, India and operated by the Indian Institute of Astrophysics. Situated in the Western Himalayas at an elevation of 4,500 meters (14,764 ft), the IAO is one of the world's highest located sites for optical, infrared and gamma-ray telescopes. It is currently the tenth highest optical telescope in the world. It is India's first dark-sky preserve.

Hanle is a large historic village in the Indian union territory of Ladakh. The revenue village of Hanle comprises six hamlets — Bhok, Dhado, Punguk, Khuldo, Naga and Tibetan Refugee habitation —within 1073 sq km Changthang Wildlife Sanctuary in Changthang plateau. It is the site of the 17th-century Hanle Monastery (gompa) of the Drukpa Kagyu branch of Tibetan Buddhism. Hanle is located in the Hanle River valley on an old branch of the ancient Ladakh–Tibet trade route. Hanle is the home of Hanle observatory, the tenth highest optical telescope in the world in India's first dark-sky preserve.