the first Astronomer Royal, appointed in 1675 by King Charles II in response to the need to find a reliable means of measuring longitude at sea. Flamsteed had recommended obtaining more accurate measurements of the movements of the Moon and the positions of the stars. The Royal Observatory at Greenwich was built for him. Flamsteed’s catalogue of 2935 stars, Historia coelestis Britannica, was published posthumously in 1725 and was the first major star catalogue compiled with the aid of a telescope. Four years later a set of star charts based on the catalogue, Atlas coelestis, appeared.