Smithsonian Astrophysical Observatory Star Catalog
Encyclopedia
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
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.
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...
. It was published by the Smithsonian Astrophysical Observatory
Smithsonian Astrophysical Observatory
The Smithsonian Astrophysical Observatory is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory to form the Harvard-Smithsonian Center for Astrophysics .-History:The SAO was founded in 1890 by...
in 1966 and contains 258,997 stars. The catalogue was
compiled from various previous astrometric catalogues, and contains only stars to about ninth magnitude
Apparent 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...
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
Declination
In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...
, with stars sorted by right ascension
Right ascension
Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:...
within each band.
Examples of SAO catalogue entries
- SAO 67174 is VegaVegaVega is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus...
. - SAO 113271 is BetelgeuseBetelgeuseBetelgeuse, also known by its Bayer designation Alpha Orionis , is the eighth brightest star in the night sky and second brightest star in the constellation of Orion, outshining its neighbour Rigel only rarely...
. - SAO 40012 is HD 277559HD 277559HD 277559 is a F-type star in the constellation of Auriga. It has an apparent visual magnitude of approximately 9.66....
. - SAO 158687SAO 158687HD 128598 is a star.The star was used to discover Uranus' rings. When Uranus occulted this star, it twinkled, revealing the presence of a ring system....
is the star that was occultedOccultationAn occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...
by UranusUranusUranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...
in March 1977, leading to the discovery of rings around UranusRings of UranusThe planet Uranus has a system of rings intermediate in complexity between the more extensive set around Saturn and the simpler systems around Jupiter and Neptune. The rings of Uranus were discovered on March 10, 1977, by James L. Elliot, Edward W. Dunham, and Douglas J. Mink...
.