National Geographic Society – Palomar Observatory Sky Survey
   HOME

TheInfoList



OR:

The National Geographic Society – Palomar Observatory Sky Survey (NGS-POSS, or just POSS, also POSS I) was a major
astronomical survey An astronomical survey is a general celestial cartography, map or astrophotography, image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of image ...
, that took almost 2,000
photographic plates Photographic plates preceded photographic film, film as the primary medium for capturing images in photography. These plates, made of metal or Glass, glass and coated with a light-sensitive Photographic emulsion, emulsion, were integral to early ...
of the night sky. It was conducted at
Palomar Observatory The Palomar Observatory is an astronomical research observatory in the Palomar Mountains of San Diego County, California, United States. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...
, California, United States, and completed by the end of 1958.


Observations

The photographs were taken with the Samuel Oschin telescope at Palomar Observatory, and the astronomical survey was funded by a grant from the
National Geographic Society The National Geographic Society, headquartered in Washington, D.C., United States, is one of the largest nonprofit scientific and educational organizations in the world. Founded in 1888, its interests include geography, archaeology, natural sc ...
to the
California Institute of Technology The California Institute of Technology (branded as Caltech) is a private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small group of institutes ...
. Among the primary minds behind the project were
Edwin Hubble Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. Hubble proved that many objects previously ...
, Milton L. Humason, Walter Baade,
Ira Sprague Bowen Ira Sprague Bowen (December 21, 1898 – February 6, 1973) was an American physicist and astronomer. In 1927 he discovered that nebulium was not really a chemical element but instead doubly ionized oxygen. Life and work Bowen was born in Sen ...
and Rudolph Minkowski. The first photographic plate was exposed on November 11, 1949. 99% of the plates were taken by June 20, 1956, but the final 1% was not completed until December 10, 1958.N. Reid & S. Djorgovski (1993) The Second Palomar Sky Survey
/ref> The survey utilized square photographic plates, covering about 6 ° of sky per side (approximately 36 square degrees per plate). Each region of the sky was photographed twice, once using a red sensitive
Kodak The Eastman Kodak Company, referred to simply as Kodak (), is an American public company that produces various products related to its historic basis in film photography. The company is headquartered in Rochester, New York, and is incorporated i ...
103a-E plate, and once with a blue sensitive Kodak 103a-O plate. This allowed the color of celestial objects to be recorded. The survey was originally meant to cover the sky from the north celestial pole to -24° declination. This figure specifies the position of the plate center, hence the actual coverage under the original plan would have been to approximately -27°. It was expected that 879 plate pairs would be required. However the Survey was ultimately extended to -30° plate centers, giving irregular coverage to as far south as -34° declination, and utilizing 936 total plate pairs. The limiting magnitude of the survey varied depending on the region of the sky, but is commonly quoted as 22nd
magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...
on average.


Publication

The NGS-POSS was published shortly after the Survey was completed as a collection of 1,872 photographic negative prints each measuring 14" x 14". In the early 1970s there was another "printing" of the Survey, this time on 14" x17" photographic negative prints. The California Institute of Technology bookstore used to sell prints of selected POSS regions. The regions were chosen to support educational exercises and the set was a curriculum teaching tool. In 1962, the Whiteoak Extension, comprising 100 red-sensitive plates extending coverage to -42° declination, was completed and published as identically sized photographic negative prints. The Whiteoak Extension is often found in libraries stored as an appendix or companion to the photographic print edition of the NGS-POSS. This brings the number of prints to 1,972 for most holders of a photographic edition of the NGS-POSS. In 1981, a set of NGS-POSS Transparency Overlay Maps was published by Robert S. Dixon of the
Ohio State University The Ohio State University (Ohio State or OSU) is a public university, public Land-grant university, land-grant research university in Columbus, Ohio, United States. A member of the University System of Ohio, it was founded in 1870. It is one ...
. This work is commonly found wherever a photographic print edition of the NGS-POSS is held.


Derivative works

Many
astronomical catalog An astronomical catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, Galaxy morphological classification, morphology, origin, means of detection, or method of discovery. The olde ...
s are partial derivatives of the NGS-POSS (e.g.
Abell Catalog of Planetary Nebulae The Abell Catalog of Planetary Nebulae was created in 1966 by George Ogden Abell, George O. Abell and was composed of 86 entries thought to be planetary nebulae. The objects were collected from discoveries, about half by Albert George Wilson ...
), which was used for decades for purposes of cataloging and categorizing celestial objects, especially in studies of galaxy morphology. Innumerable
astronomical object An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ''body'' are of ...
s were discovered by astronomers studying the NGS-POSS photographs. In 1986, work was begun on a digital version of the NGS-POSS. Eight years later, the scanning of the original NGS-POSS plates was completed. The resulting digital images were compressed and published as the
Digitized Sky Survey The Digitized Sky Survey (DSS) is a digital data, digitized version of several photography, photographic astronomical surveys of the night sky, produced by the Space Telescope Science Institute between 1983 and 2006. Versions and source materia ...
in 1994. The Digitized Sky Survey was made available on a set of 102 CD-ROMs, and can also be queried through several web interfaces. In 1996, an even more compressed version, RealSky, was marketed by the Astronomical Society of the Pacific. in 2001, a catalog identifying over 89 million objects on the NGS-POSS was placed online as part of the Minnesota Automated Plate Scanner Catalog of the POSS I. The catalog was also distributed in a set of 4 DVD-ROMs. The catalog contains accurate sky positions and brightness measurements for all of these objects as well as more esoteric parameters such as ellipticity, position angle, and concentration index.


See also

* Southern Sky Survey * Palomar Observatory Sky Survey II * Two Micron All-Sky Survey *
Sloan Digital Sky Survey The Sloan Digital Sky Survey or SDSS is a major multi-spectral imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project began in 2000 a ...


References


External links


Digitized Sky Survey

Minnesota Automated Plate Scanner Catalog of the POSS I
{{DEFAULTSORT:National Geographic Society - Palomar Observatory Sky Survey Astronomical surveys Astronomical imaging Palomar Observatory 1958 in California 1958 in science Palomar Observatory Sky Survey