[2] While still a student, in 1889 he published a collection of translations titled Arabiske Sange og Eventyr (Arabic Songs and Fairy Tales).
When 24, he became the youngest student ever to receive a doctorate as a result of his Studier over Tusind og en Nat (Studies of A Thousand and One Nights).
[1] During the years 1891–1893, Østrup made a study trip to Egypt and Syria under primitive conditions, visiting the as yet little known Aneza Bedouin tribe.
[5] In 1898, Østrup attempted to obtain van Mehren's professorship at the University of Copenhagen but was unsuccessful, apparently owing to his preference for modern Arabic dialects rather than the traditionally taught classical idiom.
Instead he gave his address in Latin, the traditional language of academics, praising the achievements of the university and commenting on the illustrious Danes who had benefited from its curriculum.
Exchanges with his hosts, however, cast some doubt as to how many of them had followed his presentation as they appeared mainly interested in discussing how National Socialism had combated Bolshevism.