Johann Karl Burckhardt
Encyclopedia
Johann Karl Burckhardt was a German
-born astronomer
and mathematician
who later became a naturalized French
citizen. (He later became known as Jean Charles Burckhardt -- as in the engraved portrait shown here). He is remembered in particular for his work in fundamental astronomy, and for his lunar theory
, which was in widespread use for the construction of navigational ephemerides of the Moon for much of the first half of the nineteenth century.
, where he studied mathematics and astronomy. Later he became an assistant at the Gotha Observatory
and studied under Franz Xaver von Zach. On von Zach's recommendation he joined the observatory of the École militaire
in Paris, then directed by Jérôme Lalande. He was appointed as astronome-adjoint to the Bureau des Longitudes
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 École militaire
.
s of comet
s, and his study of a comet of 1770 had initially gained him some professional reputation.
In 1812 he published an improved lunar theory
, after that of Pierre-Simon Laplace
. Burckhardt's lunar tables
appear to have been the first to be based on a least squares
adjustment of the coefficients to selected lunar observations, of which about 4000 were used; and a committee of the Bureau des Longitudes
(consisting of Laplace
, Delambre, 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 the Nautical Almanac
from 1821 to 1861 (but they were superseded in part, as from 1856, for computing the lunar horizontal parallax, by improved tables due to J C Adams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 lunar theory
.
The crater Burckhardt
on the Moon
is named after him.
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
-born astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
and mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
who later became a naturalized French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
citizen. (He later became known as Jean Charles Burckhardt -- as in the engraved portrait shown here). He is remembered in particular for his work in fundamental astronomy, and for his lunar theory
Lunar theory
Lunar theory attempts to account for the motions of the Moon. There are many irregularities in the Moon's motion, and many attempts have been made over a long history to account for them. After centuries of being heavily problematic, the lunar motions are nowadays modelled to a very high degree...
, 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 LeipzigLeipzig
Leipzig Leipzig has always been a trade city, situated during the time of the Holy Roman Empire at the intersection of the Via Regia and Via Imperii, two important trade routes. At one time, Leipzig was one of the major European centres of learning and culture in fields such as music and publishing...
, where he studied mathematics and astronomy. Later he became an assistant at the Gotha Observatory
Gotha Observatory
Gotha Observatory was a German astronomical observatory located on Seeberg hill near Gotha, Thuringia, Germany...
and studied under Franz Xaver von Zach. On von Zach's recommendation he joined the observatory of the École militaire
École Militaire
The École Militaire is a vast complex of buildings housing various military training facilities located in the 7th arrondissement of Paris, France, southeast of the Champ de Mars....
in Paris, then directed by Jérôme Lalande. He was appointed as astronome-adjoint to the Bureau des Longitudes
Bureau des Longitudes
The Bureau des Longitudes is a French scientific institution, founded by decree of 25 June 1795 and charged with the improvement of nautical navigation, standardisation of time-keeping, geodesy and astronomical observation. During the 19th century, it was responsible for synchronizing clocks...
and received his letters of French naturalization as a French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
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 École militaire
École Militaire
The École Militaire is a vast complex of buildings housing various military training facilities located in the 7th arrondissement of Paris, France, southeast of the Champ de Mars....
.
Scientific Work
Burckhardt carried out extensive studies on the orbitOrbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
s of comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s, and his study of a comet of 1770 had initially gained him some professional reputation.
In 1812 he published an improved lunar theory
Lunar theory
Lunar theory attempts to account for the motions of the Moon. There are many irregularities in the Moon's motion, and many attempts have been made over a long history to account for them. After centuries of being heavily problematic, the lunar motions are nowadays modelled to a very high degree...
, after that of Pierre-Simon Laplace
Pierre-Simon Laplace
Pierre-Simon, marquis de Laplace was a French mathematician and astronomer whose work was pivotal to the development of mathematical astronomy and statistics. He summarized and extended the work of his predecessors in his five volume Mécanique Céleste...
. Burckhardt's lunar tables
Lunar theory
Lunar theory attempts to account for the motions of the Moon. There are many irregularities in the Moon's motion, and many attempts have been made over a long history to account for them. After centuries of being heavily problematic, the lunar motions are nowadays modelled to a very high degree...
appear to have been the first to be based on a least squares
Least squares
The method of least squares is a standard approach to the approximate solution of overdetermined systems, i.e., sets of equations in which there are more equations than unknowns. "Least squares" means that the overall solution minimizes the sum of the squares of the errors made in solving every...
adjustment of the coefficients to selected lunar observations, of which about 4000 were used; and a committee of the Bureau des Longitudes
Bureau des Longitudes
The Bureau des Longitudes is a French scientific institution, founded by decree of 25 June 1795 and charged with the improvement of nautical navigation, standardisation of time-keeping, geodesy and astronomical observation. During the 19th century, it was responsible for synchronizing clocks...
(consisting of Laplace
Pierre-Simon Laplace
Pierre-Simon, marquis de Laplace was a French mathematician and astronomer whose work was pivotal to the development of mathematical astronomy and statistics. He summarized and extended the work of his predecessors in his five volume Mécanique Céleste...
, Delambre, Bouvard
Alexis Bouvard
Alexis Bouvard was a French astronomer. He is particularly noted for his careful observations of the irregularities in the motion of Uranus and his hypothesis of the existence of an eighth planet in the solar system.-Life:...
, Arago
François Arago
François Jean Dominique Arago , known simply as François Arago , was a French mathematician, physicist, astronomer and politician.-Early life and work:...
and Poisson) concluded after an early form of sum-of-squares
Squared deviations
In probability theory and statistics, the definition of variance is either the expected value , or average value , of squared deviations from the mean. Computations for analysis of variance involve the partitioning of a sum of squared deviations...
analysis that Burckhardt's tables improved on those of Bürg
Johann Tobias Bürg
Johann Tobias Bürg was an Austrian astronomer.Born in Vienna, Bürg worked as a professor and astronomer in Klagenfurt, in Carinthia. He subsequently worked as astronomical assistant at the observatory at Vienna from 1792 until he retired in 1813.He published some astronomical tables on the Moon...
. Accordingly, they enjoyed for some decades a substantial reputation as the most accurate available. They were officially used for computing the lunar ephemerides
Ephemeris
An ephemeris is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Different kinds of ephemerides are used for astronomy and astrology...
in the Nautical Almanac
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 almanac ever to contain data dedicated to the convenient...
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
John Couch Adams
John Couch Adams was a British mathematician and astronomer. Adams was born in Laneast, near Launceston, Cornwall, and died in Cambridge. The Cornish name Couch is pronounced "cooch"....
). 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
Peter Andreas Hansen
Peter Andreas Hansen was a Danish astronomer, was born at Tønder, Schleswig.-Biography:The son of a goldsmith, Hansen learned the trade of a watchmaker at Flensburg, and exercised it at Berlin and Tønder, 1818–1820...
's more comprehensive lunar theory
Lunar theory
Lunar theory attempts to account for the motions of the Moon. There are many irregularities in the Moon's motion, and many attempts have been made over a long history to account for them. After centuries of being heavily problematic, the lunar motions are nowadays modelled to a very high degree...
.
The crater Burckhardt
Burckhardt (crater)
Burckhardt is a lunar impact crater that is located in the northeast part of the Moon. It lies between the craters Geminus just to the north and Cleomedes to the south....
on the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
is named after him.