Fritz was appointed Professor of Astronomy at Caltech in 1942 and also worked as a research director/consultant for Aerojet Engineering Corporation (1943–1961) and staff member of Mount Wilson Observatory and Palomar Observatory for most of his career.
Na Caltechu je 1942. postavljen za profesora astronomije, a također je radio kao istraživački ravnatelj i savjetnik za Inženjersku korporaciju Aerojet (1943.-1961.) i član tima na Opservatoriju Mount Wilson i Palomaru najvećim dijelom svoje karijere.