Durchmusterung
Encyclopedia
In astronomy
, Durchmusterung or Bonner Durchmusterung (BD), is the usual name for three comprehensive astrometric
star catalogue
s of the whole sky, processed by the Bonn
Observatory (Germany
) from 1859 to 1903.
Today, the term Durchmusterung includes not only stars but also the search for other celestial objects. Special tasks are the celestial scanning in electromagnetic wavelengths
which are shorter or longer than visible light
waves.
The name comes from Durchmusterung ("run-through examination"), a German word used for a systematic
survey of objects or data.
s of approximately 325,000 stars to apparent magnitude 9–10. It was the basis for an excellent star atlas (some 100 pages) and for the AGK
and SAO
catalogues of the 20th century. The BD star number
s are still used and allow the correlation of this pioneering work with modern projects.
The format of a BD number is exemplified by BD-16 1591 which is the BD number of Sirius
. The -16 component is the declination of Sirius, and 1591 a leaping number.
and the solar system
, up to the nascent field of astrophysics
— were essentially supported by Atlas and data of the Bonner Durchmusterung. But some decades later the positional accuracy began to be insufficient for more exact projects. Further the BD could not cover the whole sky, because far southern stars are not visible from Germany
.
So the scientific community
decided to supplement the Southern Sky by two additional astrometric surveys which should be carried out by observatories
located at the Southern hemisphere
: Córdoba
, Argentina
, and Cape Town
, South Africa
.
The Cordoba Durchmusterung (abbreviated CD, or, less commonly, CoD) was made visually — similar to the former BD), but the Cape Photographic Durchmusterung (CPD) was conducted by the new photographic technique, which just before was shown to have sufficient accuracy.
Similar to the BD numbers, the southern star
s are identified by CD and CPD numbers.
To establish a more exact reference
system for the Bonner Durchmusterung, in the late 19th century the astronomers and geodesists began to work on a Celestial
Fundamental Co-ordinate System, based on the Earth's rotation axis, the vernal equinox
and the Ecliptic
plane. This astrometric project led to the Fundamental Catalogue of the Berlin
observatory and was used as an exact coordinate frame for the BD and AGK. It was modernized in the 1920s (FK3, mean accuracy ±1"), up to the present FK6 as the latest step of cosmic geodesy
(accuracy 0.1"). Together with radioastronomical
measurements the FK6 accuracy is now better than ±0.1".
satellite, operated between 1989-93, which observed around 118,000 stars over the whole sky, and led to three very accurate star catalogues:
In the next decade a further step is planned using a future satellite, Gaia
. The Gaia catalogue plans to include around one billion stars, with an apparent magnitude limit of around 20. Therefore, it will include a sufficient number of stars of our galaxy
to assist future projects of modern space science with greater accuracy and wider sample size.
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
, Durchmusterung or Bonner Durchmusterung (BD), is the usual name for three comprehensive astrometric
Astrometry
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our Galaxy, the Milky...
star catalogue
Star catalogue
A star catalogue, or star catalog, is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some...
s of the whole sky, processed by the Bonn
Bonn
Bonn is the 19th largest city in Germany. Located in the Cologne/Bonn Region, about 25 kilometres south of Cologne on the river Rhine in the State of North Rhine-Westphalia, it was the capital of West Germany from 1949 to 1990 and the official seat of government of united Germany from 1990 to 1999....
Observatory (Germany
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...
) from 1859 to 1903.
Today, the term Durchmusterung includes not only stars but also the search for other celestial objects. Special tasks are the celestial scanning in electromagnetic wavelengths
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
which are shorter or longer than visible light
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
waves.
The name comes from Durchmusterung ("run-through examination"), a German word used for a systematic
Systematic
Systematic is an American hard rock band from Oakland, California. They were one of the first signings to Metallica drummer Lars Ulrich's record label, The Music Company, via Elektra Records. The band released two studio albums before disbanding in 2004....
survey of objects or data.
Original
The 44 years work of the Bonner Durchmusterung (abbreviated by BD) tabulates the positions and apparent magnitudeApparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
s of approximately 325,000 stars to apparent magnitude 9–10. It was the basis for an excellent star atlas (some 100 pages) and for the AGK
Astronomische Gesellschaft Katalog
The Astronomische Gesellschaft Katalog is an astrometric star catalogue. Compilation for the first version, AGK1, was started in 1861 by Friedrich Argelander and published between 1890 and 1954, listing 200 000 stars down to ninth magnitude....
and SAO
Smithsonian Astrophysical Observatory Star Catalog
The Smithsonian Astrophysical Observatory Star Catalog is an astrometric star catalogue. It was published by the Smithsonian Astrophysical Observatory in 1966 and contains 258,997 stars. The catalogue was...
catalogues of the 20th century. The BD star number
Star number
A star number is a centered figurate number that represents a centered hexagram, such as the one that Chinese checkers is played on.The nth star number is given by the formula 6n + 1...
s are still used and allow the correlation of this pioneering work with modern projects.
The format of a BD number is exemplified by BD-16 1591 which is the BD number of Sirius
Sirius
Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek: Seirios . The star has the Bayer designation Alpha Canis Majoris...
. The -16 component is the declination of Sirius, and 1591 a leaping number.
Extension
Many astronomical projects — from studies of celestial mechanicsCelestial mechanics
Celestial mechanics is the branch of astronomy that deals with the motions of celestial objects. The field applies principles of physics, historically classical mechanics, to astronomical objects such as stars and planets to produce ephemeris data. Orbital mechanics is a subfield which focuses on...
and the solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
, up to the nascent field of astrophysics
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
— were essentially supported by Atlas and data of the Bonner Durchmusterung. But some decades later the positional accuracy began to be insufficient for more exact projects. Further the BD could not cover the whole sky, because far southern stars are not visible from Germany
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...
.
So the scientific community
Scientific community
The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science. Objectivity is expected to be achieved by the scientific method...
decided to supplement the Southern Sky by two additional astrometric surveys which should be carried out by observatories
Observatory
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geology, oceanography and volcanology are examples of disciplines for which observatories have been constructed...
located at the Southern hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
: Córdoba
Córdoba, Argentina
Córdoba is a city located near the geographical center of Argentina, in the foothills of the Sierras Chicas on the Suquía River, about northwest of Buenos Aires. It is the capital of Córdoba Province. Córdoba is the second-largest city in Argentina after the federal capital Buenos Aires, with...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, and Cape Town
Cape Town
Cape Town is the second-most populous city in South Africa, and the provincial capital and primate city of the Western Cape. As the seat of the National Parliament, it is also the legislative capital of the country. It forms part of the City of Cape Town metropolitan municipality...
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
.
The Cordoba Durchmusterung (abbreviated CD, or, less commonly, CoD) was made visually — similar to the former BD), but the Cape Photographic Durchmusterung (CPD) was conducted by the new photographic technique, which just before was shown to have sufficient accuracy.
Similar to the BD numbers, the southern star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s are identified by CD and CPD numbers.
To establish a more exact reference
Reference
Reference is derived from Middle English referren, from Middle French rèférer, from Latin referre, "to carry back", formed from the prefix re- and ferre, "to bear"...
system for the Bonner Durchmusterung, in the late 19th century the astronomers and geodesists began to work on a Celestial
Celestial coordinate system
In astronomy, a celestial coordinate system is a coordinate system for mapping positions on the celestial sphere.There are different celestial coordinate systems each using a system of spherical coordinates projected on the celestial sphere, in analogy to the geographic coordinate system used on...
Fundamental Co-ordinate System, based on the Earth's rotation axis, the vernal equinox
Equinox
An equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator...
and the Ecliptic
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
plane. This astrometric project led to the Fundamental Catalogue of the Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
observatory and was used as an exact coordinate frame for the BD and AGK. It was modernized in the 1920s (FK3, mean accuracy ±1"), up to the present FK6 as the latest step of cosmic geodesy
Geodetic astronomy
Geodetic astronomy is the application of astronomical methods into networks and technical projects of geodesy.The most important topics are:* Establishment of geodetic datum systems Geodetic astronomy is the application of astronomical methods into networks and technical projects of geodesy.The...
(accuracy 0.1"). Together with radioastronomical
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...
measurements the FK6 accuracy is now better than ±0.1".
Modern counterparts
The most important development has been the HipparcosHipparcos
Hipparcos was a scientific mission of the European Space Agency , launched in 1989 and operated between 1989 and 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky...
satellite, operated between 1989-93, which observed around 118,000 stars over the whole sky, and led to three very accurate star catalogues:
- Hipparcos Catalogue (118,000 stars, average accuracy ±0.001")
- Tycho Catalogue (about 1,050,000 stars, with accuracy ±0.03"), and
- Tycho-2 CatalogueTycho-2 CatalogueThe Tycho-2 Catalogue is a catalogue of more than 2.5 million of the brightest stars.- Catalogue :The astrometric reference catalogue contain positions, proper motions, and two-color photometric data for the 2,539,913 of the brightest stars in the Milky Way, of which about 5000 are visible to the...
(about 2,500,000 stars) which was improved for double starDouble starIn observational astronomy, a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. This can happen either because the pair forms a binary star, i.e...
effects and proper motions using the Astrographic Catalogue observations.
In the next decade a further step is planned using a future satellite, Gaia
Gaia probe
Gaia is a European Space Agency astrometry space mission, and a successor to the ESA Hipparcos mission. It was included within the context of the ESA Horizon 2000 Plus long-term scientific programme in 2000. Arianespace expects to launch Gaia for the ESA in March 2013, using a Soyuz rocket from...
. The Gaia catalogue plans to include around one billion stars, with an apparent magnitude limit of around 20. Therefore, it will include a sufficient number of stars of our galaxy
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
to assist future projects of modern space science with greater accuracy and wider sample size.