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 aligned
wall on which the quadrant
was later mounted was built into Uraniborg at the onset.
The accuracy of this instrument,
based on comparison with eight reference stars, has been estimated
to 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 such
as these, with improved sighting devices and measuring scales,
as well as Tycho's advanced procedures to correct
for atmospheric refraction, allowed him to compute stellar
and planetary positions consistently accurate to within
seconds of arc. Tycho's determination
of the tropical year was too small by about one second, and his determination
of the Earth's orbital tilt (which Tycho, committed to the Earth's
fixity as he was, referred to as
the angle between the ecliptic and the celestial equator) by
half a minute of arc.
Tycho left Hveen in 1597, having fallen out of favor with the Danish
King Christian IV. Upon settling in Prague he arranged for most
of his instrument to be shipped there. After his death, legal battles
between Kepler and Tycho's heir led to the instruments being stored away.
All but Tychoi's great globe were destroyed in the aftermath of
the Bohemian civil war of 1619. The great globe found its way back
to 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 (fortunately
elaborate) 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
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