I gave it a question I've been trying to answer for a long time: "What star designation system does Joseph Needham use in Science & Civilization in China? What star is referred to by the designation '4339 Camelopardi' in that book"?

Fable blew me away with its detailed answer[0] showing a chain of references going from J. E. Bode's 1801 catalogue Allgemeine Beschreibung und Nachweisung der Gestirne to Gustave Schlegel's 1875 work Uranographie Chinoise. I was excited, until I checked scanned copies of the cited books and did not actually find any star with the designation "4339 Camelopardi".

Upon following up with Claude, I was forced to downgrade to Opus, which admitted that Fable's answer was likely a hallucination. Ah, well!

[0]: https://claude.ai/share/0252a3f6-3d29-4de8-a893-010181d8b4e7