In 1869 he became a professor at the University of Vienna. He was named the director of the Vienna observatory in 1878. He also served as president of the Austrian österreichischen Gradmessungskommission, the degree measurement commission.
He published a number of comet observations and emphemeris' in the Astronomische Nachrichten between 1859 and 1909. In 1892 he published "Atlas der Sternwelt", a German language astronomy atlas.
Weiss died in Vienna. The crater Weiss on the Moon is named after him.