This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Observatory gathers three observatories, each built under the patronage of a religious or royal authority that treated the accurate reading of the sky as its own responsibility.
The Vatican Observatory, established in its present form by Leo XIII in 1891 and based at Castel Gandolfo, continues a papal patronage of astronomy older than the institution itself, running back through earlier Roman observatories to the calendar work behind the Gregorian reform of 1582. It also operates a research group at the University of Arizona and a telescope on Mount Graham, and most of its staff astronomers are Jesuits.
The Maragheh Observatory was built in 1259 in northwestern Iran under the Mongol Ilkhanid ruler Hulagu and directed by the Persian polymath Nasir al-Din al-Tusi, who persuaded Hulagu that his astronomical tables needed a purpose built institution. Financed through waqf, the Islamic charitable endowment, it kept operating for more than fifty years after Tusi's death, and its scholars produced the Zij-i Ilkhani tables, later used by Ibn al-Shatir and, some historians argue, transmitted onward to Copernicus.
The Ulugh Beg Observatory was built in the 1420s near Samarkand by the Timurid ruler and astronomer Ulugh Beg, who directed its scholars personally. Its giant curved sextant, cut partly into a hillside, produced a star catalogue and astronomical tables accurate enough to be referenced in European astronomy for centuries, the last major observatory of the classical Islamic astronomical tradition before Ulugh Beg's assassination in 1449 scattered its instruments and scholars.
Across a Catholic papacy and two Islamic courts three centuries apart, the pattern repeats: a ruler's patronage, and results that outlasted the ruler.