Astronomical survey

An astronomical survey is a general map or 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 images, spectra, or other observations of objects that share a common type or feature. Surveys are often restricted to one band of the electromagnetic spectrum due to instrumental limitations, although multiwavelength surveys can be made by using multiple detectors, each sensitive to a different bandwidth.[1]

Surveys have generally been performed as part of the production of an astronomical catalog. They may also search for transient astronomical events. They often use wide-field astrographs.

Scientific value

Sky surveys, unlike targeted observation of a specific object, allow astronomers to catalog celestial objects and perform statistical analyses on them without complex corrections for selection effects. In some cases, an astronomer interested in a particular object will find that survey images are sufficient to make new telescope time entirely unnecessary.

Surveys also help astronomers choose targets for closer study using larger, more powerful telescopes. If previous observations support a hypothesis, a telescope scheduling committee is more likely to approve new, more detailed observations to test it.

The wide scope of surveys makes them ideal for finding foreground objects that move, such as asteroids and comets. An astronomer can compare existing survey images to current observations to identify changes; this task can even be performed automatically using image analysis software. Besides science, these surveys also detect potentially hazardous objects. Similarly, images of the same object taken by different surveys can be compared to detect transient astronomical events such as variable stars.[2]

List of sky surveys
  • Radio
    • Third Cambridge Catalogue of Radio Sources ("3C") - Survey at 159 and 178 MHz published in 1959
    • HIPASS – Radio survey, the first blind HI survey to cover the entire southern sky. 1997–2002
    • Ohio Sky Survey – Over 19,000 radio sources at 1415 MHz. 1965–1973.
    • NVSS – Survey at 1.4 GHz mapping the sky north of −40 deg
    • FIRST – Survey to look for faint radio sources at twenty cms.[11]
    • SUMSS - Survey at 843 MHz, mapping the sky south of -30 deg with similar sensitivity and resolution to the northern NVSS [12]
    • PALFA Survey – On-going 1.4 GHz survey for radio pulsars using the Arecibo Observatory.
    • GALEX Arecibo SDSS Survey GASS[13] designed to measure the neutral hydrogen content of a representative sample of ~1000 massive, galaxies
    • C-BASS – On-going 5 GHz all sky survey to aid in the subtraction of galactic foregrounds from maps of the Cosmic Microwave Background
    • EMU – A large radio continuum survey covering 3/4 of the sky, expected to discover about 70 million galaxies
    • GMRT - The Giant Metrewave Radio Telescope's TGSS ADR mapped the sky at 150 MHz.
    • HTRU – A pulsar and radio transients survey of the northern and southern sky using the Parkes Radio Telescope and the Effelsberg telescope.
  • Gamma-ray
    • Fermi Gamma-ray Space Telescope, formerly referred to as the "Gamma-ray Large Area Space Telescope (GLAST)." 2008–present; the goal for the telescope's lifetime is 10 years.
  • Multi-wavelength surveys
    • GAMA – the Galaxy And Mass Assembly survey[14] combines data from a number of ground- and space-based observatories together with a large redshift survey, performed at the Anglo-Australian Telescope. The resulting dataset aims to be a comprehensive resource for studying the physics of the galaxy population and underlying mass structures in the recent universe.[15]
    • GOODS – The Great Observatories Origins Deep Survey.
    • COSMOS – The Cosmic Evolution Survey
    • CANDELS - The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
    • (The latter three surveys are joining together observations obtained from space with the Hubble Space Telescope, the Spitzer Space Telescope, the Chandra X-ray Observatory and the XMM-Newton satellite, with a large set of observations obtained with ground-based telescopes).
    • Atlas 3d Survey – sample of 260 galaxies for the Astrophysics project.[16]
  • Planned
    • Vera C. Rubin Observatory – a proposed very large telescope designed to repeatedly survey the whole sky that is visible from its location
    • ASKAP HI All Sky Survey (WALLABY) – PI Bärbel Koribalski

Surveys of the Magellanic Clouds

See also

References
  1. See, for example, Lacy, M., Riley, J. M., Waldram, E. M., McMahon, R. G., & Warner, P. J. (1995). "A radio-optical survey of the North Ecliptic CAP". Monthly Notices of the Royal Astronomical Society. 276 (2): 614–626. Bibcode:1995MNRAS.276..614L. doi:10.1093/mnras/276.2.614.{{cite journal}}: CS1 maint: uses authors parameter (link)
  2. Gay, Dr. Pamela; Cain, Fraser (26 May 2008). "Episode #90: The Scientific Method". Astronomy Cast (Podcast). Retrieved 16 Dec 2009.
  3. "3D Map of Distant Galaxies Completed – VLT survey shows distribution in space of 90 000 galaxies". www.eso.org. Retrieved 16 December 2016.
  4. Risinger, Nick. "Phototopic Sky Survey". Retrieved 12 May 2011.
  5. Associated Press (12 May 2011). "Amateur Photographer Links 37,000 Pics in Night-Sky Panorama". Fox News. Retrieved 13 May 2011.
  6. "WiggleZ Dark Energy Survey | Home". Wigglez.swin.edu.au. Retrieved 2014-03-03.
  7. "darkenergysurvey.org". darkenergysurvey.org. Retrieved 2014-03-03.
  8. "SLUGGS survey webpage".
  9. "LAMOST survey webpage".
  10. "The Birth of Monsters". Retrieved 14 December 2015.
  11. "The VLA FIRST Survey". Sundog.stsci.edu. 2008-07-21. Retrieved 2014-03-03.
  12. "SUMSS: a wide-field radio imaging survey of the southern sky - II. The source catalogue". Monthly Notices of the Royal Astronomical Society. pp. 1117–1130.
  13. "The GALEX Arecibo SDSS Survey". Mpa-garching.mpg.de. Retrieved 2014-03-03.
  14. gama-survey.org
  15. Driver, Simon P.; Norberg, Peder; Baldry, Ivan K.; Bamford, Steven P.; Hopkins, Andrew M.; Liske, Jochen; Loveday, Jon; Peacock, John A.; Hill, D. T.; Kelvin, L. S.; Robotham, A. S. G.; Cross, N. J. G.; Parkinson, H. R.; Prescott, M.; Conselice, C. J.; Dunne, L.; Brough, S.; Jones, H.; Sharp, R. G.; Van Kampen, E.; Oliver, S.; Roseboom, I. G.; Bland-Hawthorn, J.; Croom, S. M.; Ellis, S.; Cameron, E.; Cole, S.; Frenk, C. S.; Couch, W. J.; et al. (2009). "GAMA: towards a physical understanding of galaxy formation". Astronomy & Geophysics. 50 (5): 5.12. arXiv:0910.5123. Bibcode:2009A&G....50e..12D. doi:10.1111/j.1468-4004.2009.50512.x.
  16. "Atlas3D Survey". Astro.physics.ox.ac.uk. Retrieved 2014-03-03.
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