Vienna ÖNB 5203[1] is a fifteenth-century astronomical multiple-text (and multi-graphical), miscellany manuscript conserved at the Austrian National Library (Österreichischen Nationalbibliothek).

[2] One of the main features of this codex is that it has been largely copied by the hand of Regiomontanus,[3] a famous German mathematician, astrologer and astronomer of the fifteenth century.

Apart from Regiomontanus’ autograph, Vienna ÖNB 5203 contains examples of two other scribal hands, one of which belongs to Georg von Peurbach, who was as well an astronomer, mathematician and instrument maker of Austrian origin.

After Regiomontanus’ death in 1476, his entire library, which, apart from the books, included many astronomical instruments, has passed into ownership of his collaborator from Nuremberg, Bernhard Walther (1430–1504).

One of such scholars was Johannes Schöner (1477–1547), a mathematician from the Nuremberg college who has foliated Vienna ÖNB 5203, has added titles to many treatises throughout the manuscript, as well as the list of content, and has entitled the codex “Regiomontanus’ calculation notebook”.

Regiomontanus was a pupil of Georg von Peurbach, whose works are found amongst the content of the manuscript and who has copied a part of text with his own hand.

Georg von Peurbach (variants of the name: Purbach, Peuerbach, Purbachius)[8] was an Austrian astronomer, mathematician and instrument maker of the mid-fifteenth century.

The diagrams serve as a pedagogical tool for explaining the motion of the major planets, of the Sun and the Moon, of the fixed stars (the 8th sphere) and the eclipse theory.

[13] The layout of folios 129r-133r is different from the rest of the manuscript, as Regiomontanus has left noticeably smaller margins in comparison with those observed in Theoricae Novae Planetarum.

For instance, the canon at folios 54r-58v starting "Cum diu saepe dubitarem an tabella que Solis altitudines ad horam…"[14] and entitled Compositio tabule altitudinis Solis ad omnes horas is accompanied by tables that are integrated directly in the texts[1] (in comparison to a common tradition of separating canons and tables within the manuscript, or sometimes even within two different manuscripts).