Markree Observatory, Astronomical observatory in County Sligo, Ireland

Markree Observatory is an astronomical facility in County Sligo that was equipped with telescopes and precision instruments designed for studying the night sky. The complex housed multiple specialized devices, each built for different observational and measurement purposes.

The facility was founded in 1830 and acquired a major telescope that ranked among the largest of its era. During the 1800s, it contributed to creating an extensive star catalog and to discovering celestial bodies.

The Markree Catalogue lists 60,000 stars along the ecliptic, recorded between 8 August 1848 and 27 March 1856 and issued in four volumes in 1851, 1853, 1854 and 1856. The asteroid 9 Metis was found here in 1848 by Andrew Graham, who worked as Cooper's assistant until 1860.

The observatory stands on the grounds of Markree Castle near Collooney, in County Sligo. The 13.3-inch Cauchoix refractor was mounted inside a circular wall 16 feet across, with no dome or roof above it. The Russian source describes the site as ruined and the observatory as no longer operating, so check access before travelling.

In its early years, the main telescope was exposed to weather and operated without protective covering for a long period. This unusual arrangement allowed unobstructed sky viewing but required constant care and adjustment of the equipment.