 Its foundations may have been destroyed during extensive ground works near Copernicus’ external curia.Sikorski since 1973 researched and wrote on Copernicus' observatory in Olsztyn, which contains a still-extant plaster astronomical table that was used by Copernicus from 1516 to 1521.Sikorski has been awarded Polish presidential medals for his professional work as a historian and Copernicologist