Carl Rohrbach was a teacher and amateur astronomer.
Rohrbach studied mathematics and natural sciences at the University of Leipzig . He acquired his teaching qualification in seven subjects: mathematics, physics, astronomy, geography, German, philosophy and Latin and obtained his doctorate in Geology.
After graduating, he took on a teaching position at the Arnoldischule in his hometown. Under Rohrbach's directorate, the Arnoldischule became an upper secondary school in 1916. In addition to his school work, he created aids for mathematics lessons, promoted the artificial language Esperanto and devoted himself particularly to astronomy.
Rohrbach strove all his life to popularize astronomy. Together with the astronomer Paul Harzer and the teacher and geomagnetic scientist Adolf Schmidt, he founded a local association of the Association of Friends of Astronomy and Cosmic Physics in Gotha. Rohrbach was then also on the board of this association founded by Wilhelm Foerster, which held its central assembly in Gotha in 1894. Rohrbach issued practice star maps and a craft celestial globe. He drew star maps for Stieler's hand atlas.
From 1897 to 1906 Rohrbach administered the Gotha observatory, as the state government initially did not appoint a new specialist astronomer. In 1904, on the site of the former Seeberg observatory, he had a plaque attached to an instrument pillar commemorating the 100th anniversary of the death of the founder of this facility, Duke Ernst II of Saxe-Gotha-Altenburg.
On the occasion of the inauguration of the new Arnoldischule school in 1911, the then director Rohrbach was awarded the Knight's Cross 2nd Class of the Saxon-Ernestine House Order. Today Rohrbachstrasse in Gotha-West commemorates the deserving educators.
In 1904, Rohrbach had a private observatory built on his property on Galbergsweg, which, as the Rohrbach Tower, still appears on the city's skyline today. Inside the tower was a column that was separated from the outer shell and carried a telescope with an opening width of 10 cm. The tower is crowned by a dome designed by Rohrbach. He also had the same rotating dome installed on the Arnoldischule, which he directed and was built from 1909 to 1911 as a school observatory. Later, the Zeiss works in Jena also built a corresponding type of dome.