Georg Sabler

Georg Thomas Sabler (Russian: Его́р Его́рович Са́блер or Георг Заблер, Lithuanian: Georgas Tomas Sableris; – 7 December 1865) was an astronomer and geodesist of Baltic German origin active in territories of modern-day Estonia, Lithuania, Ukraine, and Russia (then all part of the Russian Empire).

A student of Friedrich Georg Wilhelm von Struve, Sabler studied theology and mathematics at the University of Tartu. Fascinated by Struve's lectures of astronomy, Sabler participated in an expedition that measured the difference of sea levels in the Black Sea and Caspian Sea. Sabler then worked as an astronomer at Tartu Observatory and Pulkovo Observatory, and later became the director of the Vilnius University Astronomical Observatory, which received its own photoheliograph due to Sabler's efforts. The telescope was the second one produced in the world. Sabler and his assistant Matvey Gusev pioneered the photography and research of sunspots.

He was described as the "creator and pioneer of new astrophysical research at the Vilnius observatory". Sabler also constructed a star catalog, took care of the methodology of observations, and constructed various astronomical instruments such as achromatic lenses. Notably, Sabler participated in determining the Struve Geodetic Arc in Finland, Lithuania, Ukraine, and Bessarabia. Sabler was the first to find a way to determine the angle of refraction in transparent media.

Biography Early life and studies Georg Thomas Sabler was born on in Haljala, now part of Lääne-Viru County, Estonia. His father, Georg Christian Sabler (1776–1819), was a Lutheran pastor. At first, Sabler studied privately. Later, Sabler graduated from the Tartu Evangelical Cathedral's gymnasium. Sabler studied theology (1828–1832) and mathematics (1832–1839) at the University of Tartu. He developed an interest in natural sciences, especially in astronomy, which was lectured by Friedrich Georg Wilhelm von Struve. During his study years, Sabler was engaged in astronomical observations, particularly of binary stars. Some of his works were published in the scientific press. For his scientific aptitude, von Struve ensured that Sabler began working at the Tartu Observatory as an assistant to its director until 1839.

In 1836–1837 Sabler participated in an expedition that determined the difference between the sea levels of the Black Sea and Caspian Sea. Sabler sent his assistant and fellow astronomer Matvey Gusev for an internship to England in 1858–1860, where they learned of the appliance of photography in astronomy in Kew Observatory, famously pioneered by astronomer Warren De la Rue. On 19 April 1861, Sabler participated in a meeting hosted by the St. Petersburg Academy of Sciences' physics and mathematics department in Pulkovo. In the meeting, Sabler argued that the university's observatory required a solar telescope, emphasizing that the observatory should direct all efforts for astrophysics research of sunspots and star photometry instead of traditional astrometry. He was buried in the Vilnius Evangelical Lutheran Cemetery. The grave was destroyed during the Soviet occupation of Lithuania.