Tycho's Instruments

Tycho and his great quadrant at Uraniborg. Tinted engraving from Tycho's Astronomiae instaurata mechanica,published in Wansbeck in 1598. Completed in 1582, something like the mural quadrant was evidently planned upon Tycho's arrival on Hveen in 1576, since the accurately alignedwall on which the quadrantwas later mounted was built into Uraniborg at the onset. The accuracy of this instrument,based on comparison with eight reference stars, has been estimatedto 34.6 seconds of arc.

Here are other noteworthy instruments built by Tycho and his team of instrument builders, listed in chronological order:

Large instruments suchas these, with improved sighting devices and measuring scales,as well as Tycho's advanced procedures to correctfor atmospheric refraction, allowed him to compute stellarand planetary positions consistently accurate to withinseconds of arc. Tycho's determinationof the tropical year was too small by about one second, and his determinationof the Earth's orbital tilt (which Tycho, committed to the Earth'sfixity as he was, referred to asthe angle between the ecliptic and the celestial equator) byhalf a minute of arc.

Tycho left Hveen in 1597, having fallen out of favor with the DanishKing Christian IV. Upon settling in Prague he arranged for mostof his instrument to be shipped there. After his death, legal battlesbetween Kepler and Tycho's heir led to the instruments being stored away. All but Tychoi's great globe were destroyed in the aftermath ofthe Bohemian civil war of 1619. The great globe found its way backto Copenhagen, and remained in the University's observatory tower until that tower and all its content were destroyed by fire in 1728.All we know from Tycho's instruments is from his (fortunatelyelaborate) published writings.

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.

Tycho Kepler Hevelius