Screening
As a screening (after English and Survey ) in which is astronomy a systematic search of the entire sky or a major portion thereof according to certain objects and up to a defined magnitude limit referred to.
The result of a sky survey for stars is usually a star catalog , but the aim can also be to systematically record variables or double stars . Other objects of survey are star clusters , nebulae, galaxies, or minor planets .
From Hipparchus to Comet and Sky Police
The first star catalogs originated in antiquity, u. a. by Hipparchus (135 BC) and Ptolemy (around 150 AD). Hipparch's catalog was probably caused by a supernova and already comprised 800–1000 fixed stars, that is around half of the freely visible stars. The star locations measured by both astronomers and their predecessor Aristyllos enabled them to determine good values for the precession of the earth's axis. Ptolemy adopted his list of stars in the 8th and 9th volumes of the Almagest textbook , which made it accessible to European astronomers via Arabia in the early Middle Ages.
More precise surveys of the sky were only made after the invention of the telescope . That of Flamsteed (Greenwich) acquired great importance in the last quarter of the 17th century. It became the starting point for a long series of star catalogs to which astronomy owes its metrological basis to this day. The Greenwich Observatory was u. a. founded in order to ensure nautical navigation and thus shipping through precise star locations . In the middle of the 18th century, Bradley and his assistants carried out further extensive series of observations, which Bessel later revised and included in his "Fundamenta Astronomiae" in 1818.
The best known, however, was the Bonn survey (from 1855), which is discussed below.
In the 18th century there were also catalogs of double stars , variables and nebulae - u. a. by Wilhelm Herschel and his sister from around 1780 (848 double stars or 2500 foggy objects). The French astronomer Charles Messier (1730–1817) had previously cataloged all the star clusters and nebulae visible in the small telescope . After 18 years of work, his Messier catalog with 110 objects was published, which is still used by amateur astronomers today. It is also the basis for a competition that is sometimes carried out, the Messier Marathon (visiting all 110 objects with a telescope in just one night). The reason for this catalog, however, was Messier's search for new comets , in which the many gas nebulae of the Milky Way led to some "false alarms".
By contrast, the most important nebula catalog for specialist astronomers is the New General Catalog (NGC) from the 1880s with 7840 objects. It was later expanded by the index catalog (IC) and in the 20th century a. a. by the Palomar Sky Survey (POSS).
A special kind of survey was the Sky Police , in which around a dozen European observatories joined forces in 1800 for the systematic search for small planets that were correctly suspected to be between the orbits of Mars and Jupiter. Four of these “asteroids” had been discovered by 1807; today, several hundred thousand of them are known from automatic CCD surveys.
Bonn survey and recent projects
The Bonn survey (BD), which was carried out visually from 1852 to 1862 by astronomer Friedrich Wilhelm Argelander and his assistants , became the astrometric basis for many decades . It recorded 325,037 stars in the declination range between 89 ° and −2 ° up to an apparent magnitude of 9.5. Because of the enormous scope of the task, it was limited to an accuracy in the range of a few angular seconds . The catalog stars were also published as a sky atlas with 36 sheets for the northern sky.
Argelander's successor Eduard Schönfeld expanded the Bonn survey from 1875 to 1881 to include the southern survey , which, with 134,000 stars, reached almost to the southern horizon of Bonn. The Córdoba Survey (CD), named after the Argentine observatory in Córdoba, followed for the southern sky . It even extends up to the limit magnitude 10.0 mag and therefore includes 578,000 stars between −22 ° declination and the south celestial pole, about 40% more stars per degree than its Bonn model.
The Astronomical Society later organized cooperative surveys of several observatories in order to develop the AGK2 catalog - and later the AGK3 . The number of stars was comparable to that of the Bonn and Córdoba surveys, but the accuracy was much higher. Modern star catalogs are now mainly based on astrophotographic images of the sky, which are combined into a uniform system with the help of very carefully measured fundamental stars .
The survey from the Hipparcos satellite was a milestone. The Astrometriesatellit took in the years before 2000 the sky with a telescope in two different accuracies. The result is the Hipparcos catalog with 108,000 stars (± 0.002 "each) and the Tycho-2 catalog with 2.5 million stars at ± 0.02".
The Gaia mission , which has been running since 2013, provides the most precise sky measurements . The two preliminary catalogs Gaia DR1 from 2016 and Gaia DR2 from 2018 provided star locations of 1.1 and 1.7 billion stars, as well as quasars, double stars and asteroids.
Today, the term “survey” also means the systematic search for non-stellar celestial objects. Important projects are e.g. B. automatic periodic surveys of the sky to near-Earth asteroids ( near earth objects , NEA). Several focal points also apply to surveys in short and long wave areas of the electromagnetic spectrum , such as the search for X-ray sources , galaxy clusters or quasars . On the other hand, the search for exoplanets does not take place systematically across the sky, but rather concentrates on individual "suspicious" stars in the sun's surroundings.
list
| Surname | Waveband | Searched area | description | date |
|---|---|---|---|---|
| Bonn survey | optically | north of 22 ° south | ≈ 325,000 stars | 1852-1862 |
| Cordoba Survey | optically | South of 22 ° South | ≈ 578,000 stars | 1892-1914 |
| Pan-Andromeda Archaeological Survey (PANDAS) | optically | Andromeda Galaxy and Triangle Nebula | Exploring these galaxies with the Canada-France-Hawaii Telescope . | 2008-2010 |
| Palomar Observatory Sky Survey (POSS) | optically | northern and equatorial area | Photographic screening | 1948-1958 |
| Digitized Sky Survey | optically | completely | Photographic screening | 1994 |
| Sloan Digital Sky Survey (SDSS) | optical - spectroscopic | ≈ 1/3 of the celestial sphere | 2000–2006 (first run) | |
| Photopic Sky Survey | optically | 37,440 individual destinations | Amateur photography | 2010-2011 |
| Palomar Distant Solar System Survey (PDSSS) | optically | ± 30 ° around the ecliptic | Search for Sedna -like asteroids | 2007-2008 |
| Infrared Astronomical Satellite (IRAS) | Infrared, 12, 25, 60, and 100 μm | completely | first space telescope for MIR and FIR | 1983 |
| Two Micron All Sky Survey (2MASS) | Infrared, 1.25, 1.65, and 2.17 μm (J, H and K s bands) | completely | 1997-2001 | |
| ASTRO-F | Infrared | NIR complete, MIR & FIR 94% | Japanese satellite survey | 2006-2008 |
| Wide-Field Infrared Survey Explorer (WISE) | Infrared, 3.3, 4.7, 12, and 23 µm | 99% | NASA satellite | 2009-2010 |
| SCUBA-2 All Sky Survey | Submillimeter, 850 µm | northern and equatorial area | A survey performed with the James Clerk Maxwell Telescope | since 2011 |
| HI Parkes All Sky Survey | Radio; 21 cm ( HI line , 1,420 MHz) | south of approx. 55 ° north | southern complement to NVSS | 1997-2002 |
| Ohio Sky Survey | Radio (1415 MHz) | 63 ° N-36 ° S | 19,000 objects | 1965-1973 |
| NRAO VLA Sky Survey (NVSS) | Radio (1.4 GHz) | north of 40 ° south | carried out with the VLA | 1993-1996 |
| Fermi Gamma-ray Space Telescope | Gamma radiation | Space telescope | since 2008 | |
| Galaxy And Mass Assembly survey (GAMA) | Multi-wavelength screening | 2008-2013 | ||
| Great Observatories Origins Deep Survey (GOODS) | Multi-wavelength screening | Hubble or Chandra Deep Field | since 2001 | |
| Cosmic Evolution Survey (COSMOS) | Multi-wavelength screening | Territory in the constellation Sextant | Hubble Space Telescope u. a. | 2002-2005 |
| Hipparcos catalog | optically | completely | 118,000 stars, Hipparcos space telescope | 1989-1993 |
| Tycho-1 catalog | optically | completely | 1,000,000 stars, Hipparcos space telescope | 1989-1993 |
| Tycho 2 catalog | optically | completely | 2,500,000 stars, Hipparcos space telescope | 2000 |
| Gaia | optical, spectrophotometric , bright objects also spectroscopic | (complete) | As of Gaia DR2 in 2018, 1.7 billion stars have been released. Further publications with more objects and more precise data are planned. | since 2014 |
See also
Web links
Individual evidence
- ↑ Archive link ( Memento of the original from April 14, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Nick Risinger: Phototopic Sky Survey . Retrieved May 12, 2011.
- ↑ Associated Press: Amateur Photographer Links 37,000 pics in Night-Sky Panorama . In: Fox News , May 12, 2011. Retrieved May 13, 2011.
- ^ Schwamb et al .: Properties of the Distant Kuiper Belt: Results from the Palomar Distant Solar System Survey . In: The Astrophysical Journal . 2010. bibcode : 2010ApJ ... 720.1691S .
- ↑ a b COSMOS Project Summary ( Memento from May 8, 2015 in the Internet Archive )
- ↑ [1]
- ↑ http://www.cv.nrao.edu/nvss/
- ↑ Condon, JJ, Cotton, WD, Greisen, EW, Yin, QF, Perley, RA, Taylor, GB, & Broderick, JJ, The NRAO VLA sky survey, 1998, AJ, 115, 1693. [2]
