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 Humboldt-Universität zu Berlin (german: Humboldt-Universität zu Berlin, abbreviated HU Berlin) is a German public research university in the central borough of Mitte in Berlin. It was established by Frederick William III on the initiative o ...

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 Leibniz Institute for Astrophysics Potsdam (AIP) is a German research institute. It is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory Potsdam (AOP) founded in 1874. The latter was the world's first o ...

. Early in his career as an astronomer he aided German solar astronomer Gustav Spörer in his work to observe

sun spot Sunspots are phenomena on the Sun's photosphere that appear as temporary spots that are darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection. Sun ...

activity. Kempf joined an 1882 German expedition to

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

to observe the

transit of Venus frameless, upright=0.5 A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a trans ...

across the Sun. He was then part of

solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six month ...

missions to

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

in 1887 and 1914. 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 8.5 found in the

Bonner Durchmusterung In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, compiled by the Bonn Observatory in Germany from 1859 to 1903. The name comes from ('run-through examination'), a German word used for ...

. 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. 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.

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