Hipparchus star catalog

Rediscovery

Contrary to Ptolemy's later star catalogue, which has survived in the Almagest and the Handy Tables, there was little evidence of the material presence, and content of the star catalog of Hipparchus. The Commentary on the Phaenomena, his sole surviving work, discusses earlier works on positional astronomy by Eudoxus of Cnidus and Aratus of Soli. Only a few references by authors after Hipparchus reflect stellar coordinates; these are mostly found in the work of Aratus.

During a multispectral image survey of the ancient Greek palimpsest known as the Codex Climaci Rescriptus in 2012, Jamie Klair, then an undergraduate student at Cambridge University, noticed that some of the folios' undertext had an astronomical nature. The folios of the Codex had been erased by the ninth or tenth century, and were reused to write Syriac translations of texts by John Climacus, a sixth century Chrisitan monk. Researchers believe that other palimpsests in Saint Catherine's Monastery of the Mount Sinai, where the Codex Climaci Rescriptus was found, may contain more fragments of the star catalog.

In 2021, Peter Williams made the first observation of the existence of astronomical measurements. Folios 47–54 and 64 of the palimpsest were originally part of an old codex that contained Aratus' Phaenomena and related writings, which were dated to the fifth or sixth century CE based on palaeographic evidence.