Astronomical observatory of Palermo, Astronomical observatory in Palazzo dei Normanni, Palermo, Italy

The Giuseppe S. Vaiana Astronomical Observatory occupies the upper floors of the Palazzo dei Normanni in Palermo. It is a research facility of the National Institute for Astrophysics, with domes on the roof that were rebuilt in lighter copper after earlier iron versions proved too heavy. Its instruments include the Ramsden Circle and a Troughton equatorial telescope.

Ferdinand I of the Two Sicilies founded the observatory in 1790 on the urging of Francesco d'Aquino, Prince of Caramanico, making it Italy's oldest astronomical observatory. Giuseppe Piazzi, appointed director, obtained the Ramsden Circle and in 1801 identified Ceres, naming it Cerere Ferdinandea. Pietro Tacchini's solar research there led to the Society of Italian Spectroscopists in 1871.

The observatory's name honours Giuseppe Salvatore Vaiana, its director from 1976 to 1991. Its historic instruments are kept as a museum collection, and the Ramsden Circle remains the centrepiece: Piazzi had to press the London maker personally and overcome British reluctance to export it. The gold medal for Ceres was refused and its value spent on a Troughton equatorial telescope for the second dome.

The observatory is accessible within the Norman Palace, and visitors should inquire in advance about opening hours and available tours. The location requires climbing to the upper floors since the facility sits within a historic building.

The observatory houses the Palermo Circle, a high-precision measuring instrument made by Jesse Ramsden that transformed how astronomers measured celestial positions. This rare device stands as one of the most important instruments in the history of modern astronomy.