Dellen, Vil’gel’m (Vasilii) Karlovich
Born 1820 in Jelgava, now in the Latvian SSR; died 1896 in Iur’ev, now Tartu, Estonian SSR. Russian astronomer. Corresponding member of the St. Petersburg Academy of Sciences (1871).
Dellen graduated from the University of Dorpat (Tartu) in 1839; he was a student of V. Ia. Struve. From 1844 to 1890 he worked as an astronomer-observer at the Pulkovo Observatory. He worked out a method of determining time using a portable transit instrument set up on the vertical of the North Star.