| Published | 2000  |
|---|---|
The Tycho-2 Catalogue is an astronomical catalogue of more than 2.5 million of the brightest stars.
| Published | 2000 |
|---|---|
The Tycho-2 Catalogue is an astronomical catalogue of more than 2.5 million of the brightest stars.
The astrometric reference catalogue contain positions, proper motions, and two-color photometric data for 2,539,913 of the brightest stars in the Milky Way. Components of double stars with separations down to 0.8 arcseconds are included. The catalogue is 99% complete to magnitudes of V~11.0 and 90% complete to V~11.5. (, [1] Table 1)
The Tycho-2 positions and magnitudes are based on the observations collected by the star mapper of the European Space Agency's Hipparcos satellite. They are the same observations used to compile the Tycho-1 Catalogue (ESA SP-1200, 1997). However, Tycho-2 is much larger and a bit more precise, because a more advanced reduction technique was used.
The U.S. Naval Observatory (USNO) first compiled the ACT Reference Catalog, (Astrographic Catalogue / Tycho) containing nearly one million stars, by combining the Astrographic Catalogue (AC 2000) with the Tycho-1 Catalogue; the large epoch span between the two catalogues improved the accuracy of proper motions by about an order of magnitude. Tycho-2 now supersedes the ACT.
Proper motions precise to about 2.5 milliarcseconds per year are given as derived from a comparison with the Astrographic Catalogue (AC 2000) and 143 other ground-based astrometric catalogues, all reduced to the Hipparcos celestial coordinate system. There were only about 100,000 stars for which proper motion could not be derived. For stars brighter than Vt=9, the astrometric error is 7 milliarcseconds. The overall error for all stars is 60 milliarcseconds. The observational period was from 1989.85 to 1993.21 and the mean satellite observation epoch is 1991.5.
Photometric accuracy for stars brighter than Vt=9 is 0.013 magnitude; for all stars it is 0.10 magnitude.
To enable rapid access of specific stars in the catalogue, WCSTools software numbers each star using its Guide Star region number (0001 to 9537) and a five-digit star number within each region, separated by a decimal point. sty2 lists Tycho-2 stars by number or sky region. imty2 lists the Tycho-2 stars within an IRAF or FITS image using the world coordinate system defined in its header.
A Perl program for extracting data from the catalogue is available from http://archive.eso.org/ASTROM/. Tycho-2 File Formats WCSTools software uses the files catalog.dat and index.dat.
The following FTP sites make the Tycho-2 catalogue available as 20 gzipped files. After retrieving them and the index.dat file, combine the gzipped files into catalog.dat. The resulting files will differ from the files on the CD-ROM in that they will end lines with only a linefeed, while the CD-ROM version for which WCSTools software was written terminates lines with a carriage return and a linefeed. Add the carriage returns to the files using the unix2dos -ascii command.
Put the catalog.dat and index.dat files in a subdirectory data/ to the directory pointed to by the TY2_PATH environment parameter or the ty2cd variable in libwcs/ty2read.c.
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and our galaxy, the Milky Way.
A star catalogue 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 of the more frequently quoted ones. Star catalogues were compiled by many different ancient people, including the Babylonians, Greeks, Chinese, Persians, and Arabs. They were sometimes accompanied by a star chart for illustration. Most modern catalogues are available in electronic format and can be freely downloaded from space agencies' data centres. The largest is being compiled from the spacecraft Gaia and thus far has over a billion stars.
Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant stars.
The Carte du Ciel and the Astrographic Catalogue were two distinct but connected components of a massive international astronomical project, initiated in the late 19th century, to catalogue and map the positions of millions of stars as faint as 11th or 12th magnitude. Twenty observatories from around the world participated in exposing and measuring more than 22,000 (glass) photographic plates in an enormous observing programme extending over several decades. Despite, or because of, its vast scale, the project was only ever partially successful – the Carte du Ciel component was never completed, and for almost half a century the Astrographic Catalogue part was largely ignored. However, the appearance of the Hipparcos Catalogue in 1997 has led to an important development in the use of this historical plate material.
Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky. This permitted the first high-precision measurements of the intrinsic brightnesses, proper motions, and parallaxes of stars, enabling better calculations of their distance and tangential velocity. When combined with radial velocity measurements from spectroscopy, astrophysicists were able to finally measure all six quantities needed to determine the motion of stars. The resulting Hipparcos Catalogue, a high-precision catalogue of more than 118,200 stars, was published in 1997. The lower-precision Tycho Catalogue of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. Hipparcos' follow-up mission, Gaia, was launched in 2013.
The Guide Star Catalog (GSC), also known as the Hubble Space Telescope, Guide Catalog (HSTGC), is a star catalog compiled to support the Hubble Space Telescope with targeting off-axis stars. GSC-I contained approximately 20,000,000 stars with apparent magnitudes of 6 to 15. GSC-II contains 945,592,683 stars out to magnitude 21. As far as possible, binary stars and non-stellar objects have been excluded or flagged as not meeting the requirements of Fine Guidance Sensors. This is the first full sky star catalog created specifically for navigation in outer space.
Nu Scorpii is a multiple star system in the constellation of Scorpius. It is most likely a septuple star system, consisting of two close groups that are separated by 41 arcseconds. Based on parallax measurements, it is approximately 470 light-years from the Sun.
The Washington Double Star Catalog, or WDS, is a catalog of double stars, maintained at the United States Naval Observatory. The catalog contains positions, magnitudes, proper motions and spectral types and has entries for 141,743 pairs of double stars. The catalog also includes multiple stars. In general, a multiple star with n components will be represented by entries in the catalog for n-1 pairs of stars.
26 Aurigae is a binary star system in the northern constellation of Auriga. It is visible to the naked eye as a faint star with an apparent visual magnitude of 5.41.
24 Cancri is a triple star system in the constellation Cancer. The system is located about 226 light-years away, based on its parallax. The system has a combined apparent magnitude of 6.5, and the two components A and B are separated by 5.7″.
In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, compiled by the Bonn Observatory in Germany from 1859 to 1903. The name comes from Durchmusterung, a German word used for a systematic survey of objects or data. The term has sometimes been used for other astronomical surveys, including not only stars, but also the search for other celestial objects. Special tasks include celestial scanning in electromagnetic wavelengths shorter or longer than visible light waves.
The Smithsonian Astrophysical Observatory Star Catalog is an astrometric star catalogue, created by Smithsonian Institution, a research institute. It was published by the Smithsonian Astrophysical Observatory in 1966 and contains 258,997 stars. The catalogue was compiled from various previous astrometric catalogues, and contains only stars to about ninth magnitude for which accurate proper motions were known. Names in the SAO catalogue start with the letters SAO, followed by a number. The numbers are assigned following 18 ten-degree bands of declination, with stars sorted by right ascension within each band.
Sigma Cassiopeiae is a binary star in the constellation Cassiopeia. It is approximately 5000 light years from Earth and has a combined apparent magnitude of +4.88.
14 Eridani is a star in the equatorial Eridanus constellation. It has an apparent visual magnitude of 6.143 and is moving closer to the Sun with a radial velocity of around −5 km/s. The measured annual parallax shift is 29.26 mas, which provides an estimated distance of about 121 light years. Proper motion studies indicate that this is an astrometric binary.
HD 36678 is single star in the northern constellation of Auriga. This star is dimly visible to the naked eye with an apparent visual magnitude of 5.83. It is located at a distance of approximately 840 light years from the Sun based on parallax.
Lambda Muscae, Latinized from λ Muscae, and often catalogued HD 102249 or HIP 57363, is the fourth-brightest star in the Southern Hemisphere constellation of Musca. Lambda Muscae visibly makes up the far end of the tail of the visual Musca constellation. It is a star in a dual system according to studies, and one of the stars catalogued in astronomer Johann Bayer's 1603 publications Uranometria. Lambda Muscae more recently has been recorded as having a stellar classification of A7III. Thus, Lambda Muscae has a white tint and burns significantly hotter than the Sun.
Catalog of 5,268 Standard Stars Based on the Normal System N30 is the 1952 auxiliary star catalogue created by Herbert Rollo Morgan to address proper motion inaccuracies in 19th century observations by converting contemporary catalogues from a mean epoch around 1900 to epoch and equinox 1950.0. However, the positions were derived from more than 70 recent catalogs with epochs of observation between 1917 and 1949. The N30 system is independent from any other astrometric system. Independent proper motions were determined by comparing the 1930 normal positions with the normal positions at the mean epoch, 30 years earlier, in the Albany General Catalogue, corrected by Morgan in 1948. Its primary use is the incorporation of 19th century astronomical data into modern research, and includes Harvard photometric magnitude, Henry Draper (HD) spectral type, and proper motion.
x2 Centauri is a star located in the constellation Centaurus. It is also known by its designations HD 108114 and HR 4724. The apparent magnitude of the star is about 5.7, meaning it is only visible to the naked eye under excellent viewing conditions. Its distance is about 440 light-years, based on its parallax measured by the Hipparcos astrometry satellite.
V915 Scorpii is an orange hypergiant variable star in the constellation Scorpius.
The Gaia catalogues are star catalogues created using the results obtained by Gaia space telescope.