Paul Friedrich Ferdinand Kempf (3 June 1856 – 16 February 1920) was a German astronomer.
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).[1] On 1 July the same year he became an assistant at the Astrophysical Institute Potsdam.[2]
Early in his career as an astronomer he aided German solar astronomer Gustav Spörer in his work to observe sun spot activity.[3] Kempf joined an 1882 German expedition to Chile to observe the transit of Venus across the Sun.[4] He was then part of solar eclipse missions to Russia in 1887 and 1914.[3] In 1886, he was promoted to full astronomer and began a collaboration with his friend, German astronomer Gustav Müller to perform a massive survey of northern stars with magnitudes brighter than 7.5 found in the Bonner Durchmusterung. This work was published between 1894 and 1906, with the completed so-called Potsdamer Photometrische Durchmusterung appearing in 1907.[5][6] (Full name: "Photometrische Durchmusterung des Nördlichen Himmels, anthaltend alle sterne der B.D. bis zur Grösze 7.5"[7]
In 1894 he was named as the principal observer at Potsdam.[8] Kempf became secretary to the Astronomische Gesellschaft in 1914, then added the job of treasurer, holding both posts until his death.[3] He was survived by his wife, Helene Marie Emilie Kempf, who became one of the first two female members of the Astronomische Gesellschaft in 1921.[9]