Tycho's 1585 Great Equatorial Armillary
Great equatorial armillary, 3 meters in diameter. Built in 1585, this is an armillary sphere reduced to its bare essentials, and oneof Tycho's workhorse instrument. Estimated accuracy of 38.6 seconds of arc.
Bibliography:
Thoren, V.E. 1973, Journal for the History of Astronomy,4, 25.
Wesley, W.G. 1978, Journal for the History of Astronomy,9, 42.