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Johan August Hugo Gyldén (May 29, 1841 in Helsinki – November 9, 1896 in Stockholm) was a Finland-Swedish astronomer primarily known for work in celestial mechanics.
Gyldén was the son of Nils Abraham Gyldén, Professor of Classical philology at the University of Helsinki and baroness Beata Sofia Wrede. He spent his student years at his father's university, graduating as a filosofie magister from the Faculty of Physics and Mathematics in 1860. In 1871 he was called by the Royal Swedish Academy of Sciences to be its astronomer and head of the Stockholm Observatory. From 1872 he was a member of the Academy.
The crater Gyldén on the Moon is named after him, as well as 806 Gyldenia.