An early use of "astronaut" in a non-fiction publication is Eric Frank Russell's poem "The Astronaut", appearing in the November 1934 Bulletin of the British Interplanetary Society.
ɐn ˈɜːli jˈuːs ʌv "ˈæstɹənˌɔːt" ɪn ɐ nˈɑːnfˈɪkʃən pˌʌblɪkˈeɪʃən ɪz ˈɛɹɪk fɹˈæŋk ɹˈʌsəlz pˈoʊᵻm "ðɪ ˈæstɹənˌɔːt", ɐpˈɪɹɪŋ ɪnðə noʊvˈɛmbɚ nˈaɪntiːnhˈʌndɹɪd θˈɜːɾi fˈoːɹ bˈʊlɪtˌɪn ʌvðə bɹˈɪɾɪʃ ˌɪntɚplˈænɪtˌɛɹi səsˈaɪəɾi.