Olof Hiorter in 1747. Olof Hiorter Olof Petrus (or Peter) Hiorter (or Hjorter) (1696–1750) was a Swedish astronomer. After studying in the Netherlands, he was appointed lecturer at the University of Uppsala in 1732 to fill the vacant position of Anders Celsius then on his grand tour of European observatories. From 1737 onwards, he studied together with Celsius the aurora phenomenon and a number of astronomy subjects (solar eclipse, comet like the one of 1744, latitude measurements). Pehr Wilhelm Wargentin was his pupil. Hiorter was elected a member of the Royal Swedish Academy of Sciences in 1745 and appointed "Observator Regius" -
Christian Mayer (astronomer) of mathematics and physics at Heidelberg. By this age, however, he had developed a strong interest in astronomy. He was appointed Court Astronomer at Mannheim, and was tasked with selecting the instruments for the new observatories at Schwetzingen and Mannheim. With these completed, he was able to pursue his astronomical studies, and published numerous works. In 1769 he was invited to St. Petersburg to observe the transit of Venus, which he did together with Anders Johan Lexell. In 1773, the Jesuit order was dissolved by Pope Clement XIV, and consequently he was removed as Court Astronomer. However he was still