De sideribus tractatus is a 15th-century manuscript copy of De astronomia, a late 1st century BC treatise on astronomy thought to have been composed by C. Julius Hyginus, a freedman of Augustus Caesar and chief librarian of the Palatine Library in Rome. This manuscript's text is believed to have been inscribed by Francesco Buzzacarini. The artwork, attributed to Giovanni Vendramin and a Miniaturist known as the "Douce Master," is what makes it such an exceptional copy. Today, the manuscript is part of The New York Public Library's Spencer Collection and is featured in the Polonsky Exhibition of The New York Public Library Treasures.