Download Tycho Brahe's observations as ebooks for free. An outreach project with University of Southern Denmark.

The past months I have been working with the research library at University of Southern Denmark. They have a selection of genuine Tycho Brahe books, that they wanted conveyed to the public.

The project is divided into three topics

  1. Digitalization of the books Historia Coelestis (1672), Epistolarum Astronomicarum (1596) and later also De Nova Stella (1572). More on the latter book further down.
  2. X-ray analysis of the book cover of Epistolarum Astronomicarum to search for chemical elements (spoiler alert: we found poison).
  3. Fragment analysis of the medieval texts on the covers of Epistolarum Astronomicarum and De Nova Stella, respectively.


The two books Historia Coelestis (approx. 1100 pages) and Epistolarum Astronomicarum (approx. 400 pages) are owned by the research library at University of Southern Denmark. Those were digitalized into PDF and epub, and I added a table of content. None of the books were eligible for OCR, so the process was manual, i.e. reading every page and writing down the observations, dates, chapter, sub-chapter, etc. in a separate document. Additionally the illustrations in the book were cut out and collected in PDFs for the audience to enjoy without reading a whole book.

De Nova Stella (approx. 200 pages) is a part of Karen Brahes Bibliotek at Roskilde Kloster. It was not digitalized, so as a part of a collaboration, this was done by us in the library team. Again, the process was manual with high-resolution camera and a steady setup. The book is made available electronically on the SDU website, but is located in Roskilde.

X-ray analysis

The past meets the present! The cover of Epistolarum Astronomicarum is an old fragment from medieval times. We ran it though and x-ray scanner at Institute for Physics, Chemistry and Pharmacy at University of Southern Denmark and found the chemical composition of the ink and the paper. One of the elements was poisonous mercury, which was widely used in certain types of ink during those times.

The reason for using these texts (hundreds of years older than the book itself) as covers is because they are solid and robust material. The texts therefore say a lot about the time of the publication, as these texts were no longer used for reading, but only because of their solid composition.

Fragment analysis

The book covers were analyzed by researchers in medieval literature at Centre for Medieval Literature at University of Southern Denmark and revealed not only types of texts, but also peculiar spelling (errors).

The website is available in Danish here:

Also check out the media exposure: