Johann Georg Repsold (19 September 1770 – 14 January 1830) was a German astronomer and fireman. He began to make astronomic instruments mainly for his own use and his third son Adolf Repsold went on to establish a well-known astronomical instrument making company A & G. Repsold which later became A. Repsold and Sohne.
Repsold was born in Wremen near Bremerhaven to a clergyman Johann and his wife Charlotte Friederike Böhmer. Repsold initially studied for a career in theology but moved to study mathematics and drawing under Reinhard Woltmann, an Elbe River pilot who later worked for the Hamburg waterworks. In 1795 Repsold became a river pilot and in 1799 he married Eleonore Scharff, daughter of a captain in the fire brigade and in the same year, he too joined the fire brigade of Hamburg. He met the Swiss astronomer Johann Kaspar Horner who was making measurements in the Elbe river and discovered a common interest in astronomic instrument design and in 1800 he established a workshop. He began to make optical instruments as well and began a correspondence with Carl Friedrich Gauss on achromatic doublets. In 1802 he began building a private observatory, and collaborated in astronomical observations with Heinrich Christian Schumacher. In 1803 he made a transit instrument for Johann Horner and in 1815 Repsold made a meridian circle for Gauss at the Göttingen observatory in 1815. Gauss gave Repsold the plan for a heliotrope which was made in 1821. The Hamburg observatory was destroyed in the Napoleonic Wars in 1811. In 1825 a new observatory was completed at Stadtwall, and Repsold became the director, supplying instruments at his own expense with other funding from the city of Hamburg.
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