Abstract

Two sextants constructed for Tycho Brahe are preserved in the National Technical Museum in Prague. One was constructed by Erasmus Habermel, the other by Jost Bürgi. Both were made in the year 1600. To overcome the observational errors, several improvements were made in the construction of these instruments, especially in the case of Bürgi's sextant. It would appear both from these instruments and from his tables of sines that Tycho wanted to reduce the errors to one minute of arc. A replica of Bürgi's sextant, which is currently under construction, will allow the accuracy of the instrument to be tested