The Lake County Astronomical Society

Astronomy Bio...Johannes Franz Hartmann

Jay Bitterman

Johannes Franz Hartmann was born on January 11, 1865 in Erfurt, Germany to Daniel and Sopia (nee Evers) Hartmann. Hartmann was educated in Tuebingen, Berlin and Leipzig. In 1891 he received his doctoral in Leipzig in 1891. The subject of his thesis on the Earth's shadow during moon eclipses (Die Vergroesserung des Erdschattens bei Mondfinsternissen). He was employed in Vienna Austria, with de Ball and again in Leipzig with Bruns. 1896 Hartmann relocated to Potsdam were he worked with H.C. Vogel and in 1898 was elevated to 'Observer' in 1902 to 'Professor.

While he was there he became one of the prominent astrophysicists of his time. His primary focus was to define standards for wavelengths and micro-photometric instrumentation. At the time the biggest refractor, having a diameter of 80 cm, was installed but Hartmann found that its photographic capabilities were useless because the lenses were not precise enough. Hartmann perfected a method of testing telescope lenses that was named after him. When the main lens was re-figured according to his recommended method the telescope was capable and ready to be used. During his spectrographic investigations using this instrument Hartmann found clouds of calcium.

1907 Hartmann married Angelika Scherr (born 1881) in Berlin-Wilmersdorf. In 1909 he became the Director of the Goettingen Observatory and Professor at the University. In 1921 he traveled to La Plata because Goettingen had poor observational conditions. While there he developed a theory on Novae and discovered that the minor planet Eros was not spherical. He returned to Goettingen in 1934 due to an illness where he died on September 13, 1936. He left two sons and one daughter