Tycho Brahe
Observations of planetary motions
Copenhagen

Gained fame for a book about supernova of 1572
Supported by King of Denmark to build super naked eye observatory on an island off the Danish coast.
observations of planetary positions to better than 1/2 minute of arc (60 arc minutes = 1 degree)
At Prague near end of life (died 1601)
The more accurate the data are, the more difficult it is to find a model for the solar system to fit them.

Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA soper@bovine.uoregon.edu