Johann Karl Burckhardt (30 April 1773 – 22 June 1825) was a German-born

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

. He later became a naturalized French citizen and became known as Jean Charles Burckhardt. He is remembered in particular for his work in fundamental astronomy, and for his

lunar theory Lunar theory attempts to account for the motions of the Moon. There are many small variations (or perturbations) in the Moon's motion, and many attempts have been made to account for them. After centuries of being problematic, lunar motion can now ...

, which was in widespread use for the construction of navigational ephemerides of the Moon for much of the first half of the nineteenth century.

Life and career

Burckhardt was born in

Leipzig Leipzig ( , ; Upper Saxon: ) is the most populous city in the German state of Saxony. Leipzig's population of 605,407 inhabitants (1.1 million in the larger urban zone) as of 2021 places the city as Germany's eighth most populous, as wel ...

, where he studied

mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

and

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

. Later he became an assistant at the

Gotha Observatory Gotha Observatory (''Seeberg Observatory'', ''Sternwarte Gotha'' or ''Seeberg-Sternwarte'') was a German astronomical observatory located on Seeberg hill near Gotha, Thuringia, Germany. Initially the observatory was dedicated to astrometry, geodet ...

and studied under

Franz Xaver von Zach Baron Franz Xaver von Zach (''Franz Xaver Freiherr von Zach''; 4 June 1754 – 2 September 1832) was a Hungarian astronomer born at Pest, Hungary (now Budapest in Hungary). Biography Zach studied physics at the Royal University of Pest, and se ...

. On von Zach's recommendation he joined the observatory of the

École militaire École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

in Paris, then directed by

Jérôme Lalande Joseph Jérôme Lefrançois de Lalande (; 11 July 1732 – 4 April 1807) was a French astronomer, freemason and writer. Biography Lalande was born at Bourg-en-Bresse (now in the département of Ain) to Pierre Lefrançois and Marie‐Anne‐Gab ...

. He was appointed as ''astronome-adjoint'' to the ''

Bureau des Longitudes Bureau ( ) may refer to: Agencies and organizations *Government agency *Public administration * News bureau, an office for gathering or distributing news, generally for a given geographical location * Bureau (European Parliament), the administrat ...

'' and received his letters of French naturalization as a French citizen in 1799, and was elected to the '' L'Institut National des Sciences et des Arts'' in 1804. After Lalande's death in 1807, Burckhardt became director of the observatory at the

. He was elected a Foreign Honorary Member of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and ...

in 1822.

Scientific work

Burckhardt carried out extensive studies on the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

s of

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

s, and his study of a comet of 1770 had initially gained him some professional reputation. In 1812 he published an improved

, after that of

Pierre-Simon Laplace Pierre-Simon, marquis de Laplace (; ; 23 March 1749 – 5 March 1827) was a French scholar and polymath whose work was important to the development of engineering, mathematics, statistics, physics, astronomy, and philosophy. He summarized ...

. Burckhardt's lunar tables appear to have been the first to be based on a

least squares The method of least squares is a standard approach in regression analysis to approximate the solution of overdetermined systems (sets of equations in which there are more equations than unknowns) by minimizing the sum of the squares of the res ...

adjustment of the coefficients to selected lunar observations, of which about 4000 were used; and a committee of the

(consisting of

Laplace Pierre-Simon, marquis de Laplace (; ; 23 March 1749 – 5 March 1827) was a French scholar and polymath whose work was important to the development of engineering, mathematics, statistics, physics, astronomy, and philosophy. He summarized ...

Delambre Jean Baptiste Joseph, chevalier Delambre (19 September 1749 – 19 August 1822) was a French mathematician, astronomer, historian of astronomy, and geodesist. He was also director of the Paris Observatory, and author of well-known books on th ...

, Bouvard, Arago and Poisson) concluded after an early form of sum-of-squares analysis that Burckhardt's tables improved on those of Bürg. Accordingly, they enjoyed for some decades a substantial reputation as the most accurate available. They were officially used for computing the lunar

ephemerides In astronomy and celestial navigation, an ephemeris (pl. ephemerides; ) is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and possibly vel ...

the Nautical Almanac ''The Nautical Almanac'' has been the familiar name for a series of official British almanacs published under various titles since the first issue of ''The Nautical Almanac and Astronomical Ephemeris'', for 1767: this was the first nautical alm ...

from 1821 to 1861 (but they were superseded in part, as from 1856, for computing the lunar horizontal parallax, by improved tables due to J C Adams). Burckhardt's tables were eventually replaced altogether, for issues of the Nautical Almanac for 1862 and thereafter, by new computations based on P A Hansen's more comprehensive

.Explanatory Supplement to the Astronomical Ephemeris, (London, 1961), sect.7B, pp.177-8. The crater

Burckhardt Burckhardt, or (de) Bourcard in French, is a family of the Basel patriciate, descended from Christoph (Stoffel) Burckhardt (1490–1578), a merchant in cloth and silk originally from Münstertal, Black Forest, who received Basel citizenship i ...

on the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

is named after him.

References

Bibliography

* Burckhardt, 1794, ''Methodus combinatorio-analytica, evolvendis fractionum continuarum valoribus maxime idonea'', Leipzig. {{DEFAULTSORT:Burckhardt, Johann Karl 19th-century French astronomers 18th-century German astronomers 1773 births 1825 deaths Fellows of the American Academy of Arts and Sciences Members of the French Academy of Sciences Scientists from Leipzig 18th-century German mathematicians 19th-century French mathematicians