Career
In 1878 was awarded a doctorate in astronomy from the Humboldt University of Berlin with a thesis titled Untersuchungen über die Ptolemäische Theorie der Mondbewegung (Investigations into the Ptolemaic theory of lunar movement). On 1 July the same year he became an assistant at the Astrophysical Institute Potsdam. Early in his career as an astronomer he aided German solar astronomer Gustav Spörer in his work to observe sun spot activity.
Kempf joined an 1882 German expedition to Chile to observe the transit of Venus across the Sun.
He was then part of solar eclipse missions to Russia in 1887 and 1914. This work was published between 1894 and 1906, with the completed Potsdamer Photometrische Durchmusterung appearing in 1907.
In 1894 he was named as the principal observer at Potsdam. Kempf became secretary to the Astronomische Gesellschaft in 1914, then added the job of treasurer, holding both posts until his death.
